Must, must not, should, and do not have to in Japanese sound simple until they quietly ambush you with nuance. Classic Japanese behavior, really. The good news is that once you learn a few core patterns, you can say most everyday “I have to,” “you shouldn’t,” and “you don’t need to” ideas without spiraling into grammar drama.
This guide keeps things practical. You will learn the most useful Japanese phrases with Kanji, Rōmaji, and clear English meanings, plus real example sentences so the patterns actually stick. For a broader look at Japanese study paths, you can also check the Japanese learning hub.
One tiny warning: English likes to make “must” do a lot of jobs. Japanese prefers to split those jobs into different expressions. Yes, language is dramatic like that.
The Big Picture
Here are the main ideas you will use again and again:
- ～なければならない / ～なきゃならない = must, have to
- ～なくてはいけない / ～なきゃいけない = must, have to
- ～べきだ = should, ought to
- ～てはいけない = must not, should not, not allowed to
- ～なくてもいい = do not have to, do not need to
These patterns are the backbone of obligation and permission in Japanese. If you learn them well, you can survive daily life, exams, workplace rules, and that one friend who always asks if they “really have to” do something.
Must: ～なければならない And ～なくてはいけない
These are the most common ways to say must or have to.
食べなければならない
Tabenakereba naranai
Must eat / have to eat
行かなくてはいけない
Ikanakute wa ikenai
Must go / have to go
Both are correct. In real life, people often shorten them in casual speech:
- ～なきゃならない — casual shortened form
- ～なきゃいけない — very common casual form
- ～ないといけない — also common, especially in speech
In other words, Japanese speakers often trim the grammar when they are talking fast. Efficient. Slightly ruthless. Very on brand.
| Japanese | Rōmaji | Meaning | Example | Translation |
|---|---|---|---|---|
| 勉強しなければならない | Benkyō shinakereba naranai | Must study | 試験のために勉強しなければならない。 | Shiken no tame ni benkyō shinakereba naranai. I must study for the test. |
| 早く寝なくてはいけない | Hayaku nenakute wa ikenai | Have to sleep early | 明日早いから早く寝なくてはいけない。 | Ashita hayai kara hayaku nenakute wa ikenai. I have to sleep early because I have an early day tomorrow. |
| 出さなきゃならない | Dasanakya naranai | Must submit | レポートを今日中に出さなきゃならない。 | Repōto o kyōjū ni dasanakya naranai. I must submit the report today. |
| 帰らないといけない | Kaeranai to ikenai | Have to go home | もう遅いから帰らないといけない。 | Mō osoi kara kaeranai to ikenai. It is late, so I have to go home. |
Must Not: ～てはいけない
If you want to say must not, should not, or it is not allowed, the classic pattern is ～てはいけない.
入ってはいけない
Haitte wa ikenai
Must not enter / are not allowed to enter
食べてはいけない
Tabete wa ikenai
Must not eat / should not eat
This pattern can sound strict, but the strength depends on context. A parent, a teacher, or a sign can make it feel firm. A friend might use it in a softer “you really shouldn’t” way.
| Japanese | Rōmaji | Meaning | Example | Translation |
|---|---|---|---|---|
| ここで写真を撮ってはいけない | Koko de shashin o totte wa ikenai | You must not take photos here | この場所では写真を撮ってはいけない。 | Kono basho de wa shashin o totte wa ikenai. You must not take photos in this place. |
| 夜遅くに食べてはいけない | Yoru osoku ni tabete wa ikenai | Should not eat late at night | 夜遅くに甘い物を食べてはいけない。 | Yoru osoku ni amai mono o tabete wa ikenai. You should not eat sweets late at night. |
| ここに車を止めてはいけない | Koko ni kuruma o tomete wa ikenai | Must not park here | ここに車を止めてはいけない。 | Koko ni kuruma o tomete wa ikenai. You must not park here. |
Should: ～べきだ
～べきだ means should or ought to. It often sounds like advice, judgment, or a moral recommendation. It is useful, but a little heavier than English “should.”
謝るべきだ
Ayamaru beki da
Should apologize
もっと休むべきだ
Motto yasumu beki da
Should rest more
Because it can sound strong, ～べきだ is not always the gentlest option. If you want soft advice, Japanese speakers often use other phrases instead, like ～たほうがいい, which means “had better” or “it would be better to.”
| Japanese | Rōmaji | Meaning | Example | Translation |
|---|---|---|---|---|
| 本当のことを言うべきだ | Hontō no koto o iu beki da | Should tell the truth | 本当のことを言うべきだ。 | Hontō no koto o iu beki da. You should tell the truth. |
| もっと練習すべきだ | Motto renshū suru beki da | Should practice more | 毎日もっと練習すべきだ。 | Mainichi motto renshū suru beki da. You should practice more every day. |
| 自分で考えるべきだ | Jibun de kangaeru beki da | Should think for yourself | 答えをすぐ聞くより、自分で考えるべきだ。 | Tō o sugu kiku yori, jibun de kangaeru beki da. Rather than asking for the answer right away, you should think for yourself. |
Do Not Have To: ～なくてもいい
This one is nice because it removes pressure. ～なくてもいい means do not have to, do not need to, or it is okay not to.
行かなくてもいい
Ikanakute mo ii
Do not have to go
食べなくてもいい
Tabenakute mo ii
Do not have to eat
This is different from must not. That difference matters a lot. “You do not have to do it” is not the same as “You are not allowed to do it.” Language likes making life interesting.
| Japanese | Rōmaji | Meaning | Example | Translation |
|---|---|---|---|---|
| 今日は来なくてもいい | Kyou wa konakute mo ii | You do not have to come today | 今日は来なくてもいいです。 | Kyō wa konakute mo ii desu. You do not have to come today. |
| 急がなくてもいい | Isoganakute mo ii | You do not need to hurry | まだ時間があるから急がなくてもいい。 | Mada jikan ga aru kara isoganakute mo ii. There is still time, so you do not need to hurry. |
| 全部読まなくてもいい | Zenbu yomanakute mo ii | You do not have to read everything | この本は全部読まなくてもいい。 | Kono hon wa zenbu yomanakute mo ii. You do not have to read this whole book. |
Useful Everyday Phrases
Here are more everyday phrases that use these patterns. The first few are the ones you will see all the time in real Japanese.
| Kanji | Rōmaji | English Meaning | Example Sentence | Translation |
|---|---|---|---|---|
| しなければならない | shinakereba naranai | must do | 宿題をしなければならない。 | Shukudai o shinakereba naranai. I must do homework. |
| 行かなければならない | ikanakereba naranai | must go | 今すぐ行かなければならない。 | Ima sugu ikanakereba naranai. I must go right now. |
| 見なければならない | minakereba naranai | must watch / must see | この映画を見なければならない。 | Kono eiga o minakereba naranai. I must watch this movie. |
| しなくてはいけない | shinakute wa ikenai | have to do | レポートをしなくてはいけない。 | Repōto o shinakute wa ikenai. I have to do the report. |
| 勉強しなきゃいけない | benkyō shinakya ikenai | have to study | 試験があるから勉強しなきゃいけない。 | Shiken ga aru kara benkyō shinakya ikenai. I have to study because there is an exam. |
| 休まなければならない | yasumanakereba naranai | must rest | 体調が悪いから休まなければならない。 | Taichō ga warui kara yasumanakereba naranai. I must rest because I feel unwell. |
| 食べてはいけない | tabete wa ikenai | must not eat | ここでは食べてはいけない。 | Koko de wa tabete wa ikenai. You must not eat here. |
| 入ってはいけない | haitte wa ikenai | must not enter | その部屋に入ってはいけない。 | Sono heya ni haitte wa ikenai. You must not enter that room. |
| 言うべきだ | iu beki da | should say | 正直に言うべきだ。 | Shōjiki ni iu beki da. You should say it honestly. |
| 謝るべきだ | ayamaru beki da | should apologize | 今すぐ謝るべきだ。 | Ima sugu ayamaru beki da. You should apologize right now. |
| 戻らなくてもいい | modoranakute mo ii | do not have to return | 今は戻らなくてもいい。 | Ima wa modoranakute mo ii. You do not have to come back now. |
| 覚えなくてもいい | oboenakute mo ii | do not have to memorize | 全部覚えなくてもいい。 | Zenbu oboenakute mo ii. You do not have to memorize everything. |
Curious Bit: Soft Vs Strong Advice
Japanese often gives you more than one way to say “should.”
- ～べきだ = stronger, more like a moral duty or firm advice
- ～たほうがいい = softer, more natural for everyday advice
- ～ないほうがいい = better not to
For example:
早く寝たほうがいい
Hayaku neta hō ga ii
You should sleep early / It would be better to sleep early
This is often more natural than 早く寝るべきだ in casual conversation. The second one is not wrong, but it can sound more serious, like a tiny lecture wearing a necktie.
Pattern Guide
| Pattern | Meaning | Example | Rōmaji | English |
|---|---|---|---|---|
| V-なければならない | Must, have to | 行かなければならない | Ikanakereba naranai | I must go. |
| V-なくてはいけない | Must, have to | 行かなくてはいけない | Ikanakute wa ikenai | I have to go. |
| V-てはいけない | Must not, not allowed to | 入ってはいけない | Haitte wa ikenai | You must not enter. |
| V-べきだ | Should, ought to | 読むべきだ | Yomu beki da | You should read. |
| V-なくてもいい | Do not have to | 来なくてもいい | Konakute mo ii | You do not have to come. |
| V-たほうがいい | Should, had better | 病院へ行ったほうがいい | Byōin e itta hō ga ii | You should go to the hospital. |
Practice Time
Try swapping the English idea into Japanese. No peeking. Well, only a little peeking.
- I must study. → 勉強しなければならない
- You must not smoke here. → ここでタバコを吸ってはいけない
- You should rest. → 休むべきだ / 休んだほうがいい
- You do not have to hurry. → 急がなくてもいい
- I have to leave now. → もう出なければならない
Now try changing the sentence type:
- Must do → make it negative with ～てはいけない for “must not”
- Should do → soften it with ～たほうがいい
- Have to do → use ～なければならない or ～なくてはいけない
- Do not have to do → use ～なくてもいい
Common Mistakes And Fixes
1. Mixing up “must not” and “do not have to”
間違い: 行かなくてはいけない means “you do not have to go.”
直し: It means “you have to go.”
Do not have to is 行かなくてもいい.
2. Using べきだ for every “should”
べきだ can sound strong. For everyday advice, ～たほうがいい is often safer and more natural.
3. Forgetting that てはいけない is a prohibition
食べてはいけない is not “you don’t have to eat.” It is “you must not eat.” A very different beast.
4. Making the pattern too polite or too casual by accident
You can make many of these polite by adding です at the end, especially in formal situations:
- 行かなければなりません = must go
- 入ってはいけません = must not enter
- 来なくてもいいです = you do not have to come
Quick Reference Summary
- Must / have to → ～なければならない, ～なくてはいけない
- Must not / should not / not allowed → ～てはいけない
- Should / ought to → ～べきだ
- Do not have to / do not need to → ～なくてもいい
- More natural soft advice → ～たほうがいい
If you want to test how well these patterns are landing, a quick check at the Japanese Vocabulary Test can be a neat reality check. For a broader assessment, the Japanese Placement Test JLPT is also handy.
You can also review related sentence types in requests in Japanese and reasons in Japanese, since obligation and explanation often show up in the same conversation. Language loves to travel in little packs like that.
One more useful link for extra study is this Japanese lesson, which can help reinforce how Japanese sentence patterns work in real use.
Yak takeaway: if you can remember ～なければならない for must, ～てはいけない for must not, ～べきだ for should, and ～なくてもいい for do not have to, you already have a powerful little toolkit. Not bad for a few patterns doing the work of a whole English paragraph.
