Grammar Info

N4 Lesson 7: 9/18


I wonder...

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


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



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About ~のだろうか

When using だろう (the conjugated auxiliary verb) is grouped with (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 , or なの (in the case of な-Adjectives and nouns).
  • (わたし)たちチーム()てるのだろうか
    I wonder if our team can win.
  • 彼女(かのじょ)本当(ほんとう)彼氏(かれし)()しいのだろうか
    I wonder if she actually wants a boyfriend.
  • あの(ひと)大丈夫(だいじょうぶ)なのだろうか
    I wonder if that person is okay.
  • あれ本当(ほんとう)()(もの)なのだろうか
    I wonder if that is really food.
Despite the grammatical rule relating to nominalization using (or なの), this part of the phrase is often omitted.
  • トム(わたし)(さそ)だろうか
    I wonder if Tom will invite me. ( omitted)
  • あの(ひと)本当(ほんとう)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(たか)鉛筆(えんぴつ)トム()のでしょうか
    I wonder if Tom will buy a pencil that expensive.
  • あの(くるま)キム(くるま)なのでしょうか
    I wonder if that car belongs to Kim.
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(ひと)()ていること本当(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)
  • そこ息子(むすこ)()()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.


  • (かれ)都合(つごう)(わる)(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)たらうまくなる(の)だろうか

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

  • (あと)本当(ほんとう)(いえ)()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)()つかる()だろうか

    I wonder if the criminal will be found.

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~のだろうか – Grammar Discussion

Most Recent Replies (6 in total)

  • Warrie


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

  • 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


    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?

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