-아/어야 하다
Must/should
-아/어야 하다 expresses that an action is necessary or obligatory. It's the Korean equivalent of 'must', 'should', or 'have to'.
How It Works
-아/어야 하다 is a fundamental pattern for expressing obligation. It conveys that performing an action is necessary, required, or a logical necessity.
Conjugation Rules:
1. Verb stems with a final vowel of ㅏ or ㅗ: Add -아야 하다.
- 가다 (to go) → 가 + 아야 하다 → 가야 하다
- 보다 (to see) → 보 + 아야 하다 → 봐야 하다
2. Verb stems with other final vowels (ㅓ, ㅜ, ㅡ, ㅣ, etc.): Add -어야 하다.
- 먹다 (to eat) → 먹 + 어야 하다 → 먹어야 하다
- 읽다 (to read) → 읽 + 어야 하다 → 읽어야 하다
- 만들다 (to make) → 만들 + 어야 하다 → 만들어야 하다 (regular — the ㄹ stays before the vowel ending)
3. Verbs ending in 하다: These always become 해야 하다.
- 공부하다 (to study) → 공부해야 하다
- 운동하다 (to exercise) → 운동해야 하다
4. Nouns with 이다: It becomes -(이)어야 하다.
- 학생이다 (to be a student, consonant noun) → 학생이어야 하다. For a vowel-final noun the copula contracts: 의사이다 → 의사여야 하다
This pattern is very similar to -아/어야 되다, and in most situations, they are interchangeable. A very subtle difference is that -아/어야 하다 can sometimes imply a more active or self-imposed obligation, while -아/어야 되다 can feel more passive or due to external rules/circumstances. However, for most learners, they can be treated as synonyms.
Examples (5)
- 내일 시험이 있어서 오늘 공부해야 해요.
I have an exam tomorrow, so I have to study today.
Word by Word: Tomorrow exam exists so today study must do.
- 약속을 지켜야 합니다.
You must keep your promises.
Word by Word: Promise must keep.
- 비행기를 타려면 공항에 일찍 가야 해요.
If you want to take the plane, you have to go to the airport early.
Word by Word: Airplane to ride if airport to early must go.
- 어제는 일을 다 끝내야 해서 늦게 잤어요.
Yesterday, I had to finish all my work, so I went to bed late.
This shows the past tense form, -아/어야 했다.
- 이 약은 하루에 세 번 먹어야 해요.
You have to take this medicine three times a day.
Word by Word: This medicine per day three times must eat.
Common Mistakes
Using it for a light suggestion when a softer expression is more natural.
Different Meaning이 영화가 재미있어요. 꼭 봐야 해요.Better이 영화가 재미있어요. 꼭 한번 보세요.While not grammatically wrong, '봐야 해요' (you must see it) sounds very strong, like an order. For a friendly recommendation, -아/어 보세요 ('please try seeing it') is much more natural and polite.
Incorrect conjugation with irregular verbs.
Not Quite음악을 듣어야 해요.Better음악을 들어야 해요.The verb 듣다 (to listen) is a ㄷ irregular verb. When followed by a vowel, the ㄷ changes to ㄹ. Therefore, it becomes 들어야 해요, not 듣어야 해요.
Learn This First
To express 'must/should', you need conjugation knowledge and understanding of 하다.
Related Patterns
- -아/어야 되다Have to, Must
Almost identical in meaning to -아/어야 하다. Both mean 'must' or 'have to' and are often interchangeable. -아/어야 되다 can sometimes feel slightly more passive or related to external circumstances, but the difference is very subtle.
- -(으)면 안 되다Must Not, Should Not
Expresses the opposite concept: prohibition ('must not'). While -아/어야 하다 states what is necessary, -면 안 되다 states what is forbidden. For example, '들어가야 해요' (You must enter) vs. '들어가면 안 돼요' (You must not enter).
- -지 않아도 되다Don't Have to, Not Necessary
Expresses a lack of necessity ('don't have to'). This is the direct negation of the obligation expressed by -아/어야 하다. For example, '지금 가야 해요' (You have to go now) vs. '지금 가지 않아도 돼요' (You don't have to go now).
- -아/어야겠다I Should, I Need to
Expresses a personal realization or decision to do something ('I should...', 'I'd better...'). It's similar to -아/어야 하다 but focuses more on the speaker's own thought process and intent rather than a general rule or external obligation. Ex: '피곤하네요. 이제 자야겠어요.' (I'm tired. I should go to sleep now.)
- -아/어야 되다 / -아/어야 하다Obligation Expressions
Both express obligation - learn the subtle differences between them.
Learn Next
Patterns that build on this one.