How to Say I Don’t Know and I Don’t Understand in Japanese

Japanese gives you more than one way to say “I don’t know” and “I don’t understand,” because apparently one confused face was not enough.

The good news: the main phrases are simple. The slightly sneaky news: 知りません shirimasen and 分かりません wakarimasen are not always interchangeable. One is about not having information. The other is about not grasping meaning, logic, instructions, or what just happened in that group chat.

This guide teaches the most natural ways to say “I don’t know” and “I don’t understand” in Japanese, with polite, casual, and softer versions you can actually use. For more Japanese basics, you can also browse the Learn Japanese hub.

Table of Contents

The Big Difference: 知りません And 分かりません

The two most important phrases are 知りません shirimasen and 分かりません wakarimasen. They both look like “I don’t know” in English, but Japanese separates “not knowing information” from “not understanding something.” Rude? No. Precise? Very.

Japanese	Rōmaji	Meaning	Use It When…	Example	Translation
知りません	shirimasen	I do not know	You do not have the information	彼の名前を知りません。 Kare no namae o shirimasen.	I do not know his name.
分かりません	wakarimasen	I do not understand / I do not know	You do not understand meaning, reason, instructions, or the answer	この文の意味が分かりません。 Kono bun no imi ga wakarimasen.	I do not understand the meaning of this sentence.

Here is the quick learner rule: if someone asks for a fact you do not have, use 知りません shirimasen. If something does not make sense to your brain, use 分かりません wakarimasen.

Yak Wisdom: 知りません shirimasen says “I don’t have that information.” 分かりません wakarimasen says “My brain looked at this and quietly left the room.”

How To Say “I Don’t Know” In Japanese

The standard polite phrase for “I don’t know” is 知りません shirimasen. It comes from 知る shiru, meaning “to know.” Use it when you do not know a person, place, fact, answer, name, phone number, schedule, or other information.

知りません
Shirimasen
Meaning: I do not know.
Example: その答えを知りません。
Sono kotae o shirimasen.
I do not know that answer.
知らない
Shiranai
Meaning: I don’t know. Casual.
Example: 彼がどこにいるか知らない。
Kare ga doko ni iru ka shiranai.
I don’t know where he is.
知りませんでした
Shirimasen deshita
Meaning: I did not know.
Example: 今日は休みだと知りませんでした。
Kyō wa yasumi da to shirimasen deshita.
I did not know today was a day off.
知らなかった
Shiranakatta
Meaning: I didn’t know. Casual.
Example: その話は知らなかった。
Sono hanashi wa shiranakatta.
I didn’t know that story.

A tiny caution: 知りません shirimasen can sound a little cold if someone asks something personal and you answer too sharply. It is grammatically correct, but tone matters. Japanese is often a softener Olympics.

Softer Ways To Say “I Don’t Know”

If you want to sound warmer, especially in conversation, add a soft phrase like すみません sumimasen or use ちょっと chotto. The word ちょっと literally means “a little,” but it often softens a negative answer. English has “I’m not really sure.” Japanese has ちょっと分かりません chotto wakarimasen. Same emotional cardigan.

すみません、知りません。
Sumimasen, shirimasen.
Meaning: Sorry, I do not know.
Example: すみません、その店を知りません。
Sumimasen, sono mise o shirimasen.
Sorry, I do not know that shop.
ちょっと分かりません。
Chotto wakarimasen.
Meaning: I’m not really sure / I don’t quite know.
Example: すみません、道はちょっと分かりません。
Sumimasen, michi wa chotto wakarimasen.
Sorry, I’m not really sure about the way.
よく分かりません。
Yoku wakarimasen.
Meaning: I don’t really understand / I don’t know well.
Example: その問題はよく分かりません。
Sono mondai wa yoku wakarimasen.
I don’t really understand that problem.
はっきり分かりません。
Hakkiri wakarimasen.
Meaning: I do not know clearly / I am not certain.
Example: 時間ははっきり分かりません。
Jikan wa hakkiri wakarimasen.
I do not know the time clearly.
まだ分かりません。
Mada wakarimasen.
Meaning: I do not know yet.
Example: 結果はまだ分かりません。
Kekka wa mada wakarimasen.
I do not know the result yet.

How To Say “I Don’t Understand” In Japanese

The standard polite phrase for “I don’t understand” is 分かりません wakarimasen. It comes from 分かる wakaru, meaning “to understand” or “to be clear.” Use it when you do not understand Japanese, a word, a sentence, a question, a rule, a lesson, or why your washing machine has fifteen buttons.

分かりません
Wakarimasen
Meaning: I do not understand / I do not know.
Example: 先生の質問が分かりません。
Sensei no shitsumon ga wakarimasen.
I do not understand the teacher’s question.
分からない
Wakaranai
Meaning: I don’t understand / I don’t know. Casual.
Example: この漢字が分からない。
Kono kanji ga wakaranai.
I don’t understand this kanji.
分かりませんでした
Wakarimasen deshita
Meaning: I did not understand.
Example: 説明が分かりませんでした。
Setsumei ga wakarimasen deshita.
I did not understand the explanation.
分からなかった
Wakaranakatta
Meaning: I didn’t understand. Casual.
Example: 昨日の授業は分からなかった。
Kinō no jugyō wa wakaranakatta.
I didn’t understand yesterday’s class.

Notice something useful: Japanese often uses が ga with 分かる wakaru. You say 日本語が分かりません Nihongo ga wakarimasen, literally “Japanese is not understood.” English says “I don’t understand Japanese,” because English enjoys making everything about “I.”

Useful Phrases For Japanese Learners

These are the phrases that save real conversations. They are polite enough for shops, classrooms, stations, hotels, and new acquaintances. If you only memorize one section, make it this one. Your future confused self will send flowers.

Japanese	Rōmaji	Meaning	Example	Example Rōmaji	Translation
日本語が分かりません。	Nihongo ga wakarimasen.	I do not understand Japanese.	すみません、日本語が分かりません。	Sumimasen, Nihongo ga wakarimasen.	Sorry, I do not understand Japanese.
英語が分かりますか。	Eigo ga wakarimasu ka.	Do you understand English?	すみません、英語が分かりますか。	Sumimasen, Eigo ga wakarimasu ka.	Excuse me, do you understand English?
もう一度お願いします。	Mō ichido onegai shimasu.	One more time, please.	すみません、もう一度お願いします。	Sumimasen, mō ichido onegai shimasu.	Sorry, one more time, please.
ゆっくりお願いします。	Yukkuri onegai shimasu.	Slowly, please.	すみません、ゆっくりお願いします。	Sumimasen, yukkuri onegai shimasu.	Sorry, slowly, please.
もう少しゆっくり話してください。	Mō sukoshi yukkuri hanashite kudasai.	Please speak a little more slowly.	すみません、もう少しゆっくり話してください。	Sumimasen, mō sukoshi yukkuri hanashite kudasai.	Sorry, please speak a little more slowly.
意味が分かりません。	Imi ga wakarimasen.	I do not understand the meaning.	この言葉の意味が分かりません。	Kono kotoba no imi ga wakarimasen.	I do not understand the meaning of this word.
質問が分かりません。	Shitsumon ga wakarimasen.	I do not understand the question.	すみません、質問が分かりません。	Sumimasen, shitsumon ga wakarimasen.	Sorry, I do not understand the question.
何と言いましたか。	Nan to iimashita ka.	What did you say?	すみません、何と言いましたか。	Sumimasen, nan to iimashita ka.	Sorry, what did you say?
これは何ですか。	Kore wa nan desu ka.	What is this?	すみません、これは何ですか。	Sumimasen, kore wa nan desu ka.	Excuse me, what is this?
どういう意味ですか。	Dō iu imi desu ka.	What does it mean?	「至急」はどういう意味ですか。	“Shikyū” wa dō iu imi desu ka.	What does “urgent” mean?

Polite, Casual, And Very Formal Versions

Japanese changes depending on who you are talking to. With friends, casual is fine. With strangers, staff, teachers, coworkers, or anyone you do not want to mildly alarm, polite is safer.

Japanese	Rōmaji	Meaning	Tone	Example	Translation
知らない。	Shiranai.	I don’t know.	Casual	その人は知らない。 Sono hito wa shiranai.	I don’t know that person.
知りません。	Shirimasen.	I do not know.	Polite	住所は知りません。 Jūsho wa shirimasen.	I do not know the address.
存じません。	Zonjimasen.	I do not know.	Humble / formal	詳しいことは存じません。 Kuwashii koto wa zonjimasen.	I do not know the details.
分からない。	Wakaranai.	I don’t understand.	Casual	この問題は分からない。 Kono mondai wa wakaranai.	I don’t understand this problem.
分かりません。	Wakarimasen.	I do not understand.	Polite	説明が分かりません。 Setsumei ga wakarimasen.	I do not understand the explanation.
理解できません。	Rikai dekimasen.	I cannot understand.	More formal / analytical	この資料の内容が理解できません。 Kono shiryō no naiyō ga rikai dekimasen.	I cannot understand the content of this document.

存じません zonjimasen is very polite and humble. You may hear it in customer service or business settings. If you are a beginner, you do not need to use it every day, but recognizing it is useful. It is basically 知りません shirimasen wearing a suit.

When To Use 知りません

Use 知りません shirimasen when the question is about knowledge, information, identity, or facts. If someone asks “Who is that?” “Where is it?” “What time is it?” or “Do you know this person?” this is often your phrase.

その人を知りません。
Sono hito o shirimasen.
Meaning: I do not know that person.
Example: すみません、その人を知りません。
Sumimasen, sono hito o shirimasen.
Sorry, I do not know that person.
場所を知りません。
Basho o shirimasen.
Meaning: I do not know the place.
Example: そのレストランの場所を知りません。
Sono resutoran no basho o shirimasen.
I do not know the location of that restaurant.
理由を知りません。
Riyū o shirimasen.
Meaning: I do not know the reason.
Example: 彼女が来ない理由を知りません。
Kanojo ga konai riyū o shirimasen.
I do not know the reason she is not coming.
電話番号を知りません。
Denwa bangō o shirimasen.
Meaning: I do not know the phone number.
Example: 会社の電話番号を知りません。
Kaisha no denwa bangō o shirimasen.
I do not know the company’s phone number.

When To Use 分かりません

Use 分かりません wakarimasen when the issue is understanding, clarity, ability to follow, or uncertainty about an answer. It is also common when you are asked a question and you genuinely do not know the answer, especially in class or conversation.

答えが分かりません。
Kotae ga wakarimasen.
Meaning: I do not know the answer.
Example: この質問の答えが分かりません。
Kono shitsumon no kotae ga wakarimasen.
I do not know the answer to this question.
言っていることが分かりません。
Itte iru koto ga wakarimasen.
Meaning: I do not understand what you are saying.
Example: すみません、言っていることが分かりません。
Sumimasen, itte iru koto ga wakarimasen.
Sorry, I do not understand what you are saying.
使い方が分かりません。
Tsukaikata ga wakarimasen.
Meaning: I do not know how to use it.
Example: この機械の使い方が分かりません。
Kono kikai no tsukaikata ga wakarimasen.
I do not know how to use this machine.
行き方が分かりません。
Ikikata ga wakarimasen.
Meaning: I do not know how to get there.
Example: 駅までの行き方が分かりません。
Eki made no ikikata ga wakarimasen.
I do not know how to get to the station.
違いが分かりません。
Chigai ga wakarimasen.
Meaning: I do not understand the difference.
Example: この二つの違いが分かりません。
Kono futatsu no chigai ga wakarimasen.
I do not understand the difference between these two.

Natural Add-Ons That Make You Sound Less Robotic

Real people rarely answer with only one phrase. They add “sorry,” “maybe,” “yet,” “well,” or “a little.” Japanese does the same. These small words make your Japanese sound more human and less like a vending machine with grammar.

Japanese	Rōmaji	Meaning	Example	Example Rōmaji	Translation
すみません	sumimasen	Sorry / excuse me	すみません、分かりません。	Sumimasen, wakarimasen.	Sorry, I do not understand.
ちょっと	chotto	a little / kind of / not really	ちょっと分かりません。	Chotto wakarimasen.	I’m not really sure.
よく	yoku	well / clearly	よく分かりません。	Yoku wakarimasen.	I do not really understand.
まだ	mada	not yet / still	まだ分かりません。	Mada wakarimasen.	I do not know yet.
全然	zenzen	not at all	全然分かりません。	Zenzen wakarimasen.	I do not understand at all.
たぶん	tabun	probably / maybe	たぶん知りません。	Tabun shirimasen.	I probably do not know.

全然分かりません zenzen wakarimasen is strong. It means “I do not understand at all.” Useful after fast instructions, dense grammar, or any form with tiny boxes and no mercy.

Asking For Help After You Don’t Understand

After saying you do not understand, the next move is asking for help. These phrases are practical and polite. They also keep the conversation moving, instead of leaving everyone standing there in the fog.

もう一度言ってください。
Mō ichido itte kudasai.
Meaning: Please say it one more time.
Example: すみません、もう一度言ってください。
Sumimasen, mō ichido itte kudasai.
Sorry, please say it one more time.
ゆっくり言ってください。
Yukkuri itte kudasai.
Meaning: Please say it slowly.
Example: すみません、ゆっくり言ってください。
Sumimasen, yukkuri itte kudasai.
Sorry, please say it slowly.
書いてください。
Kaite kudasai.
Meaning: Please write it.
Example: すみません、ここに書いてください。
Sumimasen, koko ni kaite kudasai.
Sorry, please write it here.
簡単な日本語でお願いします。
Kantan na Nihongo de onegai shimasu.
Meaning: In simple Japanese, please.
Example: すみません、簡単な日本語でお願いします。
Sumimasen, kantan na Nihongo de onegai shimasu.
Sorry, in simple Japanese, please.
英語でお願いします。
Eigo de onegai shimasu.
Meaning: In English, please.
Example: できれば、英語でお願いします。
Dekireba, Eigo de onegai shimasu.
If possible, in English, please.

Common Mistakes And Better Fixes

A few mistakes are extremely common. Happily, they are easy to fix once you know what is happening.

Mistake	Why It Feels Off	Better Japanese	Rōmaji	Meaning	Example
日本語を知りません。 Nihongo o shirimasen.	This sounds like “I do not know of Japanese,” not “I do not understand Japanese.”	日本語が分かりません。	Nihongo ga wakarimasen.	I do not understand Japanese.	すみません、日本語が分かりません。 Sumimasen, Nihongo ga wakarimasen. Sorry, I do not understand Japanese.
私は分かりません。 Watashi wa wakarimasen.	Not always wrong, but often unnecessary. Japanese drops “I” when clear.	分かりません。	Wakarimasen.	I do not understand.	すみません、分かりません。 Sumimasen, wakarimasen. Sorry, I do not understand.
知りません said sharply	It may sound cold, depending on tone.	すみません、ちょっと分かりません。	Sumimasen, chotto wakarimasen.	Sorry, I’m not really sure.	すみません、道はちょっと分かりません。 Sumimasen, michi wa chotto wakarimasen. Sorry, I’m not really sure about the way.
理解しません。 Rikai shimasen.	This can sound like “I refuse to understand” or simply unnatural in basic conversation.	理解できません。	Rikai dekimasen.	I cannot understand.	この説明は理解できません。 Kono setsumei wa rikai dekimasen. I cannot understand this explanation.

Mini Practice: Choose 知りません Or 分かりません

Pick the better phrase. No pressure. The grammar police are busy correcting restaurant menus.

You do not know someone’s name.
名前を知りません。
Namae o shirimasen.
I do not know the name.
You do not understand a sentence.
文が分かりません。
Bun ga wakarimasen.
I do not understand the sentence.
You do not know the answer to a question.
答えが分かりません。
Kotae ga wakarimasen.
I do not know the answer.
You do not know that restaurant.
そのレストランを知りません。
Sono resutoran o shirimasen.
I do not know that restaurant.
You do not know how to use a ticket machine.
券売機の使い方が分かりません。
Kenbaiki no tsukaikata ga wakarimasen.
I do not know how to use the ticket machine.

Quick Reference Summary

Situation	Best Phrase	Rōmaji	English	Example
You do not know a fact	知りません。	Shirimasen.	I do not know.	答えを知りません。 Kotae o shirimasen. I do not know the answer.
You do not understand	分かりません。	Wakarimasen.	I do not understand.	意味が分かりません。 Imi ga wakarimasen. I do not understand the meaning.
You want to sound softer	ちょっと分かりません。	Chotto wakarimasen.	I’m not really sure.	すみません、ちょっと分かりません。 Sumimasen, chotto wakarimasen. Sorry, I’m not really sure.
You did not know before	知りませんでした。	Shirimasen deshita.	I did not know.	ニュースを知りませんでした。 Nyūsu o shirimasen deshita. I did not know the news.
You did not understand before	分かりませんでした。	Wakarimasen deshita.	I did not understand.	説明が分かりませんでした。 Setsumei ga wakarimasen deshita. I did not understand the explanation.
You need repetition	もう一度お願いします。	Mō ichido onegai shimasu.	One more time, please.	すみません、もう一度お願いします。 Sumimasen, mō ichido onegai shimasu. Sorry, one more time, please.

Yak Takeaway

If you remember only two phrases, make them 知りません shirimasen for “I do not know” and 分かりません wakarimasen for “I do not understand.” Use 知りません shirimasen for missing information. Use 分かりません wakarimasen when the meaning, answer, instruction, or situation is not clear.

And when in doubt, soften it: すみません、ちょっと分かりません。 Sumimasen, chotto wakarimasen. “Sorry, I’m not really sure.” Polite, useful, and much better than silently nodding while your brain files a formal complaint.