-아/어야(만) 하다
Must, Have to
-아/어야(만) 하다 expresses a strong obligation or necessity, equivalent to 'must' or 'have to'. The optional particle (만) adds emphasis, meaning 'only if'.
This pattern also has a main page: -아/어야 하다 (Must/should).
How It Works
This pattern is a powerful way to express obligation, necessity, or a strict condition. It's stronger than suggestions or recommendations.
1. Conjugation
It follows the standard -아/어 conjugation rules:
- Verb/adjective stems ending in ㅏ or ㅗ: add -아야 하다.
- 가다 → 가야 하다 (must go)
- 보다 → 봐야 하다 (must see) - Verb/adjective stems ending in other vowels: add -어야 하다.
- 먹다 → 먹어야 하다 (must eat)
- 읽다 → 읽어야 하다 (must read) - 하다 verbs: become 해야 하다.
- 공부하다 → 공부해야 하다 (must study) - 이다/아니다: become 이어야/여야 하다 and 아니어야 하다.
- 학생이다 → 학생이어야 하다 (must be a student)
- 의사이다 → 의사여야 하다 (must be a doctor)
2. Usage: Obligation and Necessity
This is the most common usage, indicating a duty or something that must be done.
- 내일까지 이 보고서를 제출해야 합니다. (I must submit this report by tomorrow.)
- 약속을 지켜야 해요. (You must keep your promises.)
3. Usage: Necessary Condition
It can also express a condition that must be fulfilled for a subsequent clause to be true. In this sense, it means 'only if X, then Y'.
- 키가 120cm 이상이어야 놀이기구를 탈 수 있어요. (You must be over 120cm tall to be able to ride the attraction.)
- 시험에 합격해야 대학교에 들어갈 수 있습니다. (You must pass the exam to enter university.)
4. The Role of (만)
Adding 만 to form -아/어야만 하다 intensifies the condition, emphasizing that it is the only way. It strongly translates to 'only if'.
- 열심히 노력해야만 성공할 수 있다. (Only if you work hard can you succeed.)
5. -아/어야 하다 vs. -아/어야 되다
These two mean the same thing. The usual difference is register:
- -아/어야 하다: A little more formal, and more common in writing.
- 저는 제 가족을 지켜야 합니다. (I must protect my family.) - -아/어야 되다: A little more colloquial, and more common in everyday speech.
- 비행기 시간이 다 돼서 공항에 가야 돼요. (The flight time is near, so I have to go to the airport.)
In most sentences you can use either one.
Examples (5)
- 건강을 유지하려면 매일 운동해야 해요.
To maintain your health, you must exercise every day.
Word by Word: Health to maintain if you want every day exercise must do.
- 회의에 늦지 않으려면 지금 출발해야 합니다.
If you don't want to be late for the meeting, you have to leave now.
Word by Word: To the meeting late not to be if you want now must depart.
- 이 약은 식후 30분에 먹어야만 효과가 있습니다.
This medicine is effective only if you take it 30 minutes after a meal.
The use of '만' emphasizes that taking it at this specific time is the only way for it to be effective.
- 어제는 갑자기 일이 생겨서 밤늦게까지 일해야 했어요.
Yesterday, something came up suddenly, so I had to work until late at night.
This shows the past tense form, -아/어야 했다.
- 성인이어야만 투표할 수 있는 자격이 주어집니다.
Only if you are an adult are you given the right to vote.
Word by Word: An adult must be only if vote can do qualification is given.
Common Mistakes
Using -아야 after a stem whose last vowel is not ㅏ or ㅗ.
Not Quite내일까지 책을 읽아야 해요.Better내일까지 책을 읽어야 해요.The last vowel of 읽 is ㅣ, not ㅏ or ㅗ, so the ending is -어야, not -아야. Only stems whose last vowel is ㅏ or ㅗ take -아야, as in 가야, 봐야 and 앉아야.
Writing -이야 instead of -이어야 for 'must be' a noun.
Not Quite투표하려면 성인이야 해요.Better투표하려면 성인이어야 해요.After a noun, 이다 becomes 이어야 (or 여야 after a vowel) before 하다. Writing 이야 해요 leaves out the 어.
Learn This First
To express strong obligation 'must/have to', you need obligation patterns and emphasis.
Related Patterns
- -아/어야 되다Have to, Must
The same meaning as '-아/어야 하다'. '-아/어야 되다' is a little more colloquial, while '-아/어야 하다' is a little more formal and more common in writing. You can use either one in most sentences.
- -(으)면 안 되다Must Not, Should Not
This is the direct opposite, expressing prohibition ('must not', 'should not'). While '-아/어야 하다' states what is required, '-면 안 되다' states what is forbidden.
- -지 않아도 되다Don't Have to, Not Necessary
This expresses a lack of necessity ('don't have to'). It is the negation of the obligation expressed by '-아/어야 하다'.
- -(으)ㄹ 필요가 있다/없다Need to, Don't Need to
A softer way to express necessity. '-ㄹ 필요가 있다' means 'there is a need to', which is less forceful than the direct obligation of '-아/어야 하다'.
- -아/어야겠다I Should, I Need to
Expresses the speaker's personal realization or decision about a necessity ('I should...', 'I'd better...'). It's focused on the speaker's own intent, whereas '-아/어야 하다' states a more general or objective obligation.