文法の説明

N4 レッスン 7: 9/18

のだろうか

I wonder...

Versions without ん/の are also acceptable but sound old-fashioned

使い方・接続

Verb +（の(1)）+ だろうか
［い］Adjective +（の(1)）+ だろうか
［な］Adjective +（な + の(1)）+ だろうか
Noun +（な + の(1)）+ だろうか

(1) ん

詳細

  • 使用域

    Standard

  • 使用域

    一般

「～のだろうか」の情報

When using だろう (the conjugated auxiliary verb) is grouped with か (the question particle), it presents the statement before it as something that the speaker is unsure about. In this way, it sounds similar to 'I wonder if (A)' in English.
To use this construction, the statement before だろうか must be nominalized (turned into a noun-phrase). This is done through the use of の, or なの (in the case of な-Adjectives and nouns).
  • 私(わたし)たちのチームは勝(か)てるのだろうか。
    I wonder if our team can win.
  • 彼女(かのじょ)は本当(ほんとう)に彼氏(かれし)が欲(ほ)しいのだろうか。
    I wonder if she actually wants a boyfriend.
  • あの人(ひと)は大丈夫(だいじょうぶ)なのだろうか。
    I wonder if that person is okay.
  • あれは本当(ほんとう)に食(た)べ物(もの)なのだろうか。
    I wonder if that is really food.
Despite the grammatical rule relating to nominalization using の (or なの), this part of the phrase is often omitted.
  • トムは私(わたし)を誘(さそ)うだろうか。
    I wonder if Tom will invite me. (の omitted)
  • あの人(ひと)は本当(ほんとう)に弁護士(べんごし)だろうか。
    I wonder if that person is actually a lawyer. (なの omitted)
だろうか is quite masculine, so in order to sound more polite/ladylike, でしょうか may also be used instead.
  • そんな高(たか)い鉛筆(えんぴつ)をトムが買(か)うのでしょうか。
    I wonder if Tom will buy a pencil that expensive.
  • あの車(くるま)はキムの車(くるま)なのでしょうか。
    I wonder if that car belongs to Kim.
Caution
Although だろうか is quite masculine, it does not strictly mean that でしょうか is feminine. でしょうか may be used confidently by either women or men.
Fun Fact
Like だろう, だろうか may be used to ask a question, or simply to express the speaker's inner thoughts.
  • この人(ひと)が言(い)っていることは本当(ほんとう)なのだろうか。
    I wonder if what this person is saying is true. (Said while talking to oneself)
  • そこに息子(むすこ)を連(つ)れて行(い)っていいのだろうか？
    I wonder if I can take my son there. (Said while talking to oneself)
However, だろうか is most commonly used to express a personal 'I wonder', in a similar way to かな. Because of this, even if it is used as a question, the listener may assume that you are not specifically looking for an answer from them.

例文

  • 彼(かれ)の都合(つごう)が悪(わる)い(の)だろうか。

    I wonder if it is bad timing for him?

    • もうすぐ時間(じかん)だろうか。

      I wonder if it is about time.

      • 練習(れんしゅう)したら、うまくなる(の)だろうか。

        I wonder if I will get better at it if I practice.

        • 後(あと)で本当(ほんとう)に家(いえ)に行(い)っていいのだろうか。

          I wonder if it is really okay to go to his/her house later.

          • 犯人(はんにん)が見(み)つかる(の)だろうか。

            I wonder if the criminal will be found.

            • 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。

            「～のだろうか」に関する文法ディスカッション

            最近の返信 (合計6件)

            • Warrie

              Warrie

              What is the difference between のだろうか and かな?

            • Fuga

              Fuga

              Hey there @Warrie !

              They both mean the same thing, but they are used in different situations. かな is used in more casual situations, like texting and casual conversations, while のだろうか is usually used in writing. のだろうか is also casual, but かな sounds more casual, if that makes sense!

            • Warrie

              Warrie

              Makes sense, thank you! Maybe this info should be added to the explanations in BP. I had this question a couple of times with words with the same meaning and each time Google helped me out to explain the difference, in this case I just couldn’t find an answer.

              Or for example when I give かな as the answer and then I get a ‘let’s try a different grammatical structure here’ reply, change that into ‘let’s make it slightly more formal’ or something like that?

            「～のだろうか」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