Formal Because (-(으)므로)
-(으)므로
Formal written expression of cause/reason ('because/therefore'), used in documents and news.
Pattern
Verb/Adj stem + -(으)므로
Explanation
-(으)므로 is the formal written equivalent of -아/어서 or -(으)니까 for expressing cause and reason. It appears in legal documents, official notices, academic writing, and news: 시험이 시작되므로 핸드폰을 꺼 주시기 바랍니다 (As the exam is beginning, please turn off your phones).
Use -므로 after stems ending in a vowel or ㄹ, and -으므로 after consonants. Unlike -아/어서, tense markers can appear before -므로: 이미 결정되었으므로 변경할 수 없습니다 (Since it has already been decided, it cannot be changed).
This pattern is too formal for casual conversation. Using it in everyday speech would sound unnatural. Stick to -아/어서 or -(으)니까 in spoken Korean.
Examples
내일은 공휴일이므로 은행이 문을 닫습니다.
Naeireun gonghyuirimiuro eunhaengi muneul datseumnida.
Since tomorrow is a holiday, the bank will be closed.
안전을 위해 중요하므로 반드시 지켜 주세요.
Anjeonreul wihae jungyohamuro bandeusi jikyeo juseyo.
Since it is important for safety, please follow it without exception.
본 계약은 쌍방 합의에 의한 것이므로 효력이 있습니다.
Bon gyeyageun ssangbang habuie uihan geosimuro hyoryeogi itseumnida.
This contract is effective as it is based on mutual agreement.
Common Mistakes
Wrong
배가 고프므로 밥 먹자.
Correct
배가 고프니까 밥 먹자.
-(으)므로 is too formal for casual speech. Use -(으)니까 in conversation.
Wrong
했으므로서 완료되었습니다.
Correct
했으므로 완료되었습니다.
Don't add 서 after -(으)므로. It's a complete connector on its own.
Practice vocabulary from these grammar patterns
Build your vocabulary with science-backed spaced repetition — 30 days free.
Start Practicing