〜もの / 〜もん (reason)
mono mon
By Nihongo PathUpdated
Meaning
"because ~" — a sentence-final, emotional justification or excuse, often childish or feminine in tone.
Used to defend yourself after being questioned, frequently after だって. もん is the more casual of the two; 〜んだもの is very common.
Casual conversation between close friends or family; not for polite or written Japanese.
Formation
V = verb, N = noun, A = adjective.
Plain form + もの / もんな-adj・N + だ + もの / もんOften 〜んだもの / 〜んだもんFrequently preceded by だって
Visual diagram
〜から
neutral: because
〜ので
softer, more polite
〜んだから
insistent: you know that
〜んだもん
emotional excuse, childlike
〜から
neutral: because
〜ので
softer, more polite
〜んだから
insistent: you know that
〜んだもん
emotional excuse, childlike
Natural examples
だって、行きたくないんだもん。
だって、いきたくないんだもん。
But I just don't want to go!
食べられないよ。嫌いなんだもの。
たべられないよ。きらいなんだもの。
I can't eat it — I don't like it.
仕方ないよ。まだ子供だもの。
しかたないよ。まだこどもだもの。
It can't be helped — he's still a child.
知らなかったんだもん、仕方ないでしょう。
しらなかったんだもん、しかたないでしょう。
I didn't know, so what could I do?
Similar grammar and the difference
Completely different: a general truth or norm. Sentence-final もの (reason) has no だ after it. Compare side by side
〜から
Neutral reason. もの adds emotion and a plea for understanding.
〜んだから
Also insistent, but firm rather than sulky.
Common mistakes
- ✗
- 遅刻して申し訳ありません。電車が止まったんだもん。
- ✓
- 電車が止まってしまったものですから。
- Why
- もん is far too casual for an apology to a superior; use ものですから.
- ✗
- だって、嫌いもん。
- ✓
- だって、嫌いなんだもん。
- Why
- な-adjectives and nouns need なんだ before もん.
- ✗
- 疲れているものだ。(intended: because I'm tired)
- ✓
- 疲れているんだもの。
- Why
- Adding だ turns it into the "general truth" ものだ; the reason pattern ends in もの / もん.
Frequently preceded by だって. Very casual; avoid in formal writing. Different from 〜ものだ (general truth). The polite relative 〜ものですから is acceptable in formal speech to give a reason for a mistake.
JLPT N3 tips
On the exam
- A blank at the end of a casual reply beginning with だって is almost always もん / もの.
- If the sentence is about a general truth (人は〜), it is ものだ, not the reason もの. Check for だ.
- In listening dialogues, もん signals an excuse; use it to identify who is justifying themselves.
Frequently asked questions
What does 〜もの / 〜もん (reason) mean?
"because ~" — a sentence-final, emotional justification or excuse, often childish or feminine in tone. Used to defend yourself after being questioned, frequently after だって. もん is the more casual of the two; 〜んだもの is very common.
How do you form 〜もの / 〜もん (reason)?
Plain form + もの / もん / な-adj・N + だ + もの / もん / Often 〜んだもの / 〜んだもん / Frequently preceded by だって. V = verb, N = noun, A = adjective.
When is 〜もの / 〜もん (reason) used?
Casual conversation between close friends or family; not for polite or written Japanese.
What is the difference between 〜もの / 〜もん (reason) and 〜ものだ?
Completely different: a general truth or norm. Sentence-final もの (reason) has no だ after it.
What is the difference between 〜もの / 〜もん (reason) and 〜から?
Neutral reason. もの adds emotion and a plea for understanding.
What is a common mistake with 〜もの / 〜もん (reason)?
Wrong: 遅刻して申し訳ありません。電車が止まったんだもん。 Right: 電車が止まってしまったものですから。 もん is far too casual for an apology to a superior; use ものですから.
Quick check
「宿題やったの？」「まだ。だって、難しいんだ（ ）。」