Translation guide
The English word "seriously" has several distinct uses: as an adverb meaning "in a serious manner," as a sentence adverb to emphasize truth or importance, and as an interjection expressing surprise or disbelief. Japanese uses different expressions for each.
To do or say something earnestly, without humor or frivolity.
The most common and natural way to say "seriously" when describing an action done in earnest. Used for studying, working, discussing, etc.
真面目に勉強しなさい。
Study seriously.
He talked seriously about the issue.
Emphasizes genuine intent or commitment, often used when someone is not joking or is determined. Slightly stronger than 真面目に.
本気で言ってるの？
Are you being serious? (Are you saying that for real?)
彼は本気でプロの歌手になりたいと思っている。
He seriously wants to become a professional singer.
Conveys a grave, intense seriousness, like when lives or important matters are at stake. More weighty than 真面目に.
真剣に話を聞いてください。
Please listen seriously.
彼は真剣に将来のことを考えている。
He is seriously thinking about his future.
To stress that what you are saying is true or important, often at the beginning of a statement. Similar to "honestly" or "really."
Literally "a serious talk," used as a discourse marker to signal that you are about to say something important or sincere. Often used as "真面目な話、…"
真面目な話、今の仕事を辞めようと思ってるんだ。
Seriously, I'm thinking of quitting my current job.
Means "speaking seriously" or "to be honest." Used to preface a sincere statement.
真面目に言うと、彼の態度には本当に困っている。
Seriously, I'm really troubled by his attitude.
Literally "honestly speaking," often used like "seriously" to emphasize frankness.
正直言って、その計画は無理だと思う。
Seriously, I think that plan is impossible.
Used as an exclamation when you are shocked, can't believe something, or want confirmation. Similar to "Really?!" or "No way!"
Very common casual interjection meaning "seriously?" or "for real?" Used among friends. Can also be used as an adverb in casual speech.
A: 宝くじが当たったんだ。B: マジで？！
A: I won the lottery. B: Seriously?!
Standard word for "really?" Can be used in both casual and polite contexts. Rising intonation makes it a question.
本当に？信じられない。
Seriously? I can't believe it.
When used as a question, it asks if someone is serious or joking. Similar to "Are you serious?"
本気で言ってるの？
Seriously? Are you serious?
Literally "lie," used as an exclamation meaning "No way!" or "You're kidding!" Very casual.
うそ！マジで？
No way! Seriously?
Used to intensify an adjective or verb, meaning "very" or "extremely." Often with negative connotations like "seriously ill" or "seriously damaged."
Used for serious situations like illness, problems, or damage. Implies gravity and severity.
彼は深刻に病気だ。
He is seriously ill.
その問題を深刻に受け止めるべきだ。
We should take the problem seriously.
A versatile intensifier meaning "very" or "seriously" in the sense of "extremely." Can be used in many contexts.
Means "terribly" or "seriously" when describing something bad, like injury or damage.
彼は事故でひどくけがをした。
He was seriously injured in the accident.
All three can mean "seriously," but with different nuances. 真面目に (majime ni) is for diligent, earnest actions (studying, working). 本気で (honki de) emphasizes genuine intent or not joking. 真剣に (shinken ni) implies grave intensity, often for life-altering matters. For everyday "seriously" as in "not joking," 本気で is often best. For "seriously" as in "diligently," use 真面目に.
The loanword シリアス (shiriasu) exists but is mainly used as a noun or adjective meaning "serious" (e.g., a serious movie). Using シリアスに as an adverb is unnatural; stick to native Japanese expressions.
大変申し訳ありません。
I'm seriously sorry. (very sorry)