もの・もん
Because, Cause
Structure
い-Adj + （んだ） + もの(1)
な-Adj + （なん） + だ + もの(1)
Noun + （なん） + だ + もの(1)
(1) もん
Explanation
もの, a frequently used noun in Japanese meaning 'thing', can also function as a sentence ending particle. When used this way, it adds a subjective, emotional nuance to a statement while presenting it as a reason or excuse. Because of this, もの is often translated as 'because' or 'you see'. A more literal interpretation would be 'it's just that (A) is the case'. もの is very informal and should be reserved for casual conversation.
To use もの to state a reason, add it to the end of the plain form of a verb, adjective, or noun.
- 公園には行きたくないよ。だって、雨が降ってるもの。I don't wanna go to the park. 'Cause it's raining.
- だって、安かったもの。But 'cause it was cheap!
- このケーキは食べられないよ。今ダイエット中だもの。I can't eat this cake, 'cause I'm on a diet right now.
- 眠いに決まってるよ。きのう寝てないもの。Of course she's sleepy, 'cause she didn't sleep yesterday.
To give もの more emphasis, it is often preceded by the explanatory んだ (following a verb or い-Adjective), or なんだ (following a な-Adjective or noun).
- 遅れてごめん。だって、電車が遅れたんだもの。Sorry I'm late. It's because the train was delayed, you see.
- 一人じゃできないよ。無理なんだもの。I can't do it by myself. 'Cause it's impossible, you know.
Caution
When used as a sentence ending particle, もの is sometimes shortened to もん. This contraction sounds significantly more childish or cutesy. For this reason, it is best to avoid it in general conversation unless you specifically want to sound that way.
- まだ帰りたくないもん。'Cause I don't wanna go home yet.
- そんなのいらない！自分で買えるもん！I don't need that! 'Cause I can buy it myself!
Fun Fact
Although not frequently used in everyday Japanese, んですもの is a slightly more polite variation of んだもの that you may come across in fictional works like anime, manga, or books.
- あの方が怒るのも当然ですよ。こちらが約束を破ったんですもの。It is only natural for him to be upset. (After all,) we are the ones who broke the promise.
- しかたがないですわ。まだ学生なんですもの。It can't be helped. (Because) he's just a student, after all.
Examples
眠いんだもん。
(Because) I'm sleepy!
だって、知らなかったもの。
(Because) I didn't know!
許してよ。約束だったんだもん。
Please forgive me. (Because) it was a promise.
怖いんだもん。一人で行きたくないよ。
(Because) it's scary. I don't want to go alone.
「またゲームしてるの？」って言われても…、好きなんだもん！
Even if someone says, 'Are you playing video games again?'... (Because) I love it!
僕がこの目で見たんだもん。信じてよ。
(Because) I saw it with my own two eyes. You have to believe me!
A：「なんでこんなに下手なの？」
B：「だって初心者だもの。」
A: 'Why are you so bad at this?'
B: '(Because) I'm a beginner!'
A：「どうして会議に間に合わなかったの？」
B：「寝坊したんだもの。」
A: 'Why didn't you make it to the meeting on time?'
B: '(Because) I overslept!'
A：「どうして泣いているの？」
B：「転んで、すごく痛かったんだもん。」
A: 'Why are you crying?'
B: '(Because) I fell and it really hurt.'
A：「どうして宿題をやらなかったの？」
B：「だって、完全に忘れていたもの。」
A: 'Why didn't you do your homework?'
B: 'Well, (because) I completely forgot.'
A：「どうしてピーマンを残してるの？」
B：「嫌いなんだもん。」
A: 'Why did you leave the bell peppers?'
B: '(Because) I hate them.'
A：「パーティーに行こうよ！」
B：「疲れているから、行きたくないもん。」
A: 'Let's go to the party!'
B: 'I'm tired, so (because) I don't want to go.'