気になる means “to be on your mind”; 気にする means “to worry about” or “pay attention to.” With 気になる, something catches your attention, and が commonly marks it. With 気にする, a person attends to something, often marked by を. 気になっている can also express interest in someone.
きになる・きにする · also ki ni naru / ki ni suru / 気にしないで / 気になっている
気になる — it bothers me; I'm curious · 気にする — to let it bother you · 気にしないで — never mind
Sentences
6 sentences, word by word
気になる · something catching you
polite
。
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試験
しけん ［2］
exam; test
noun · 試験を受ける to sit one
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の
の
links noun to noun
particle · A の B = B belonging to A
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結果
けっか ［0,1］
result; outcome
noun · also 'as a result' when used adverbially
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が
が
subject marker
particle · 気になる takes が because the thing is acting on you
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気になります
きになります
is on my mind
polite 気になる · intransitive, so nothing is being done by you
気になるN3to be on one's mind
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The exam results are on my mind.
気にする · you doing the worrying
plain
。
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彼女
かのじょ ［1］
she
pronoun · third person
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は
は
as for — the topic
particle · written は, read わ
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人
ひと ［0］
other people
noun · 人の目 is a fixed phrase for others' eyes
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の
の
links noun to noun
particle · A の B = B belonging to A
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目
め ［1］
eyes; how others see you
noun · 人の目 means public opinion, not eyeballs
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を
を
object marker
particle · 気にする is transitive, so the thing takes を
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気にしすぎる
きにしすぎる
minds it too much
気にする ＋ すぎる · すぎる attaches to the ます-stem
気にするN3to mind · to let it bother you
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She cares too much what other people think.
気にしないで · comforting someone
plain
、。
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気にしないで
きにしないで
never mind; don't worry about it
negative て-form of 気にする · a request to stop doing it
気にするN3to mind · to dwell on
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君
きみ ［0］
you
pronoun · casual and slightly soft; あなた is stiffer
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の
の
links noun to noun
particle · A の B = B belonging to A
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せい
せい
fault; because of
noun · せい blames, おかげ credits
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じゃない
じゃない
isn't
negative copula · ではない in writing
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よ
よ
informing final particle
particle · offers the listener something they do not accept yet
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Don't worry about it, it wasn't your fault.
気になっている · lingering
plain
。
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彼
かれ ［1］
he
pronoun · third person
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の
の
links noun to noun
particle · A の B = B belonging to A
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言葉
ことば ［3］
words; what he said
noun · also 'language' — 日本語の言葉
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が
が
marks the subject
particle · what the sentence is about — with 好き, 分かる and potentials, the object
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ずっと
ずっと
the whole time; still
adverb · continuous duration, not 'straight'
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気になっている
きになっている
has been on my mind
気になる ＋ ている · the state that started and continues
気になるN3to be on one's mind
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Something he said has been bothering me.
あの人が気になる · the romantic sense
plain
。
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最近
さいきん ［0］
lately
noun used adverbially · no particle needed
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入った
はいった
who joined
past of 入る · modifying the noun that follows
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人
ひと ［0］
person; guy
noun · deliberately vague, which suits the sentence
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が
が
marks the subject
particle · what the sentence is about — with 好き, 分かる and potentials, the object
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ちょっと
ちょっと
kind of; a bit
adverb · hedging, which is the whole point of this sentence
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気になる
きになる
has caught my interest
気になる about a person · soft enough to deny later
気になるN3to be interested in
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I've kind of got my eye on that new guy.
気にしない · shrugging it off
plain
。
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そういう
そういう
that kind of
そう ＋ いう · modifies the noun directly, no な
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こと
こと
the act of; the fact of
noun · turns the verb in front into a noun
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は
は
as for — the topic
particle · written は, read わ
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全然
ぜんぜん ［0］
not at all
adverb · classically pairs with a negative
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気にしない
きにしない
don't mind
negative of 気にする · a stance you are taking
気にするN3to mind · to dwell on
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よ
よ
informing final particle
particle · reassuring the listener
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I really don't mind that kind of thing.
Forms
The four shapes you actually need
Thing ＋ が＋気になる
音が気になる. The thing takes が, because it is the one doing something — catching your attention.
Thing ＋ を＋気にする
人の目を気にする. The thing takes を, because you are the one acting on it. Getting this particle right is most of the battle.
気にしないで＋（ください）
Never mind. You can ask someone to stop 気にする because it is their choice; 気にならないで is not idiomatic for exactly that reason.
Person ＋ が＋気になる
あの人が気になる. About a person, 気になる usually means you are interested — the polite, deniable first step before 好き.
Meaning
Why one is なる and the other is する
Japanese draws a hard line between things that happen and things you do, and this pair sits right on it. なる is become — a change that arrives. する is do — an action you take. 気になる is your attention being caught; 気にする is you holding onto it.
That is why the particles differ.音が気になる: the sound is the subject, so が. 音を気にする: you are the subject and the sound is your object, so を. If you can name who is acting, the particle picks itself.
気にしないで is the natural comfort. You can ask somebody to stop doing something; you cannot ask them to stop having something happen to them. So a friend who is upset gets 気にしないで — don't dwell on it — and 気にならないで sounds broken to a native ear.
気になる has a second life in romance.あの人が気になる means you keep thinking about them, which in practice means you are interested. It is deliberately soft — deniable enough to say out loud, which is exactly why it is the phrase everyone reaches for first.
Inside the word
気 — the busiest character in Japanese
気 — spirit, mood, attention
One character behind a whole shelf of daily phrases: 元気 energy, 天気 weather, 気持ち feeling, 気分 mood, 人気 popularity. Reading it as “where your attention and mood live” makes most of them predictable.
The なる / する pair beyond 気
The same split runs everywhere: 決まる / 決める, 始まる / 始める, ことになる / ことにする. One member describes what happened, the other names who did it. Learning the pattern once pays off across hundreds of verbs.
気をつける — the third one
気をつけて is take care, said at goodbyes and before anything risky. Note the particle: 気を, because you are attaching your attention to something deliberately. Same 気, same logic, different verb.
Watch out
Where this pair goes wrong
Saying 気にならないで
It is not how the language works. You can ask someone to stop 気にする — it is their action — but you cannot ask them to stop having something happen to them. 気にしないで is the phrase.
Swapping the particles
音が気になる and 音を気にする. 気になる takes が and 気にする takes を, every time. Ask who is acting and the particle follows.
Reading 気になる as “I like them” too fast
About a person it does mean interest, but the point of the phrase is that it is understated. Translating it as “I like them” overshoots — “I keep thinking about them” is closer to what the speaker is admitting to.
Also asked
Questions people ask about 気になる and 気にする
What's the difference between 気になる and 気にする?
気になる happens to you — something catches your attention. 気にする is something you do — you dwell on it. That is why the first takes が and the second takes を.
Why is it 気にしないで and not 気にならないで?
Because you can only ask someone to stop an action they control. 気にする is a choice, so 気にしないで works; 気になる is involuntary, so asking someone not to do it makes no sense.
Does 気になる mean you like someone?
It means you keep thinking about them, which in practice usually means yes — but the vagueness is deliberate. It is the deniable stage before 好き, and saying it commits you to nothing.
が or を — how do I remember which?
Name who is acting. With 気になる the thing is acting on you, so it is the subject: が. With 気にする you are acting on the thing, so it is the object: を.
What does 気にしている mean?
It is bothering them and they are still turning it over — the ongoing form of 気にする. 彼はまだ気にしている means he still has not let it go, which is often said with sympathy.
Is 気をつける related?
Same character, different verb. 気をつける is to attach your attention to something — be careful. 気をつけて is what you say at a door as someone leaves, and it is one of the most-used phrases in the language.
