事になる
It will end up being, It is the result of, It has been decided that
Structure
［い］Adjective + ことになる
［な］Adjective + な + ことになる
Explanation
The expression ことになる is formed by taking the nominalizer こと (which turns a clause into a noun-like idea), adding the case marking particle に, and finishing with the う - Verb なる ('to become'). While it can mean 'to become (A)', its main function is to describe an outcome that was brought about by external factors or a natural course of events. For this reason, it is often translated as 'it has been decided that (A)', or 'it turns out that (A)'.
ことになる typically follows verbs and い-Adjectives in their attributive form. When used with a な-Adjective, な must be placed before こと.
- ちゃんと準備しないと、後で困ることになるよ。If you don't prepare properly, you'll end up in trouble later.
- このまま何も言わないと、賛成したことになる。If you don't say anything, it will be taken as you agreeing.
- 電車が遅れたせいで、約束の時間に間に合わないことになる。Because the train was late, it looks like I won't make it to my appointment on time.
The meaning of 'it has been decided that (A)' is typically reserved for verbs, as decisions inherently relate to actions that someone will carry out.
Fun Fact
This grammar point highlights why なる is frequently seen as the intransitive pair to する. する is a transitive verb, indicating that an agent performs an action. In contrast, なる is intransitive, focusing on something changing or becoming a certain way as a result. This distinction is why the (A) phrase in ことになる implies that an outcome was determined by an outside force, while keeping the focus on exactly 'what' the result turned out to be.
Examples
来月から大阪支社に転勤する事になりました。
It's been decided that I'll be transferring to the Osaka branch starting next month.
財布を忘れたので、家に戻る事になった。
I forgot my wallet, so I ended up having to go back home.
このまま練習を続けないと、試合に負ける事になるよ。
If you don't keep practicing, you'll end up losing the match.
パーティーは中止する事になりました。残念ですが。
It has been decided that the party will be canceled. It's a shame, though.
抽選で私が選ばれ、スピーチをする事になった。
I was chosen in the lottery, so I ended up having to give a speech.
来週から、この教室は使えなくなる事になりました。
It has been decided that this classroom will no longer be available for use starting next week.
電車が遅れたせいで、約束に遅れる事になった。
Because the train was late, I ended up being late for my appointment.
山田さんが新しいチームリーダーになる事になりました。
It has been decided that Mr. Yamada will be the new team leader.
急に友人が来る事になって、慌てて部屋を掃除した。
My friend ended up coming over suddenly, so I cleaned my room in a hurry.
とんでもない事になった。鍵を車の中に入れたままロックしてしまった。
We've ended up in a terrible situation. I locked my keys inside the car.
結局、私が猫の世話をする事になった。
In the end, I was the one who ended up taking care of the cat.
試験に落ちたので、もう一年勉強する事になった。
I failed the exam, so I ended up having to study for another year.