文法の説明

N3 レッスン 3: 10/22

事(こと)になる

It will end up being, It is the result of, It has been decided that

The "something has been decided" meaning only applies to verbs!

使い方・接続

Verb + ことになる
［い］Adjective + ことになる
［な］Adjective + な + ことになる

詳細

  • 使用域

    Standard

  • 使用域

    一般

「ことになる」の情報

ことになる is an expression that combines the nominalizing use of こと (creating a noun-phrase), with the case marking particle に, and the う - Verb なる 'to become'. This expression can be translated as 'to become (A)', but has the nuance that someone/thing caused (A) to become that way. Due to this, it may also be translated as 'it has been decided that (A)', or 'it will end up being (A)'.
ことになる is primarily used with verbs and い-Adjectives in their attributive form. It may also be used with な-Adjectives followed by な.
  • なんでも後回(あとまわ)しにしているとあとから苦労(くろう)することになる。
    If you wait until it is too late, you are going to end up regretting it.
  • そんなことをしたらとんでもないことになるよ。
    If you do something like that, it is going to become a huge deal.
  • 出来(でき)るだけ早(はや)く治療(ちりょう)をしないと、後(あと)から大変(たいへん)なことになる。
    If you don't treat it soon, it is going to end up being a bigger issue.
The 'it has been decided that (A)' meaning only applies to verbs, as only verbs will be enacted by someone/thing.
Fun Fact
This structure is a good example of why なる is often viewed as the intransitive form of する. する conveys that someone is performing an action (transitive), while なる implies that something is the result of an action (intransitive). This is why the (A) phrase in ことになる is usually determined to have been decided/performed by someone else, while still focusing on exactly 'what' (A) became.

例文

  • 明日(あした)が雨(あめ)ならば、１週間(しゅうかん)降(ふ)り続(つづ)くことになる。

    If it rains tomorrow, it will end up being a week straight of rain.

    Notice that when ことになる means 'end up' or 'it is the result of', it is often preceded by a conditional clause. Also, it often expresses a negative situation.

    • 震災(しんさい)のため、アメリカに帰(かえ)らなければならないことになりました。

      It was decided that I must return to America because of the earthquake.

      • インフルエンザにかかってしまったので、今日(きょう)の大会(たいかい)に出(で)れないことになった。

        Since I got the flu I ended up being unable to attend today's tournament.

        • 大変(たいへん)なことになったぞ。何(なに)か作戦(さくせん)を考(かんが)えなければ。

          We ended up getting in trouble. We have to figure out a plan.

          • この前(まえ)のように風邪(かぜ)を引(ひ)いたら、また入院(にゅういん)することになるよ。

            If you catch a cold like the last time, you will end up going to the hospital again.

            • ご登録いただくと、より多くの例文にアクセスできます。

              登録すると他の例文が見れるようになります！

            自作の例文

            自分なりの勉強をする！

            文章を追加し、Bunproの文章と一緒に勉強する。

            「ことになる」に関する文法ディスカッション

            最近の返信 (合計1件)

            • Talos

              Talos

              While showing this grammar point to my Japanese-native tutor, she claimed that several of the sentences didn’t make sense to her.

              明日が雨ならば、１週間降り続くことになる

              After I explained the meaning in English she said it would have made more sense ending in 続いたことになる 。

              インフルエンザにかかってしまったので、今日の大会が出れないことになった

              She explained that 出れない normally only takes a human subject, so I should replace が with に to get 今日の大会に出れない

              Finally, my tutor also felt that this grammar point covered two very different usages and suggested that the “was decided” meaning acts as a single grammatical unit

              ことになる

              and tends to be used in the context of a business doing the deciding. (Your example sentences might support this depending on context.)

              From example sentences with decided meaning

              • Must return to America (from a business trip?)

            「ことになる」について質問がありますか？ 話し合ったり、質問をしてみんなで学びましょう！

            ディスカッションに参加する