modality N3 common casualpolitewritten

だろうか — I wonder if ~ / perhaps ~

だろうか

Builds on だろう

Meaning

I wonder if ~ / could it be that ~ — the speaker poses an uncertain question to themselves

Key sentence

彼かれは本当ほんとうに来くるだろうか。

I wonder if he'll really come.

Formation

Attaches to	Form	Example
Verb / い-adjective (plain form)	Plain form + だろうか	間まに合あう → 間まに合あうだろうか
な-adjective / Noun (drop だ)	N / な-adj + だろうか	大丈夫だいじょうぶ → 大丈夫だいじょうぶだろうか

When: Often turned inward as a musing or rhetorical doubt rather than a question to a listener. The polite form is でしょうか. Adding の (〜のだろうか / 〜のでしょうか) makes it more reflective and searching.

Examples

この計画けいかくはうまくいくだろうか。

I wonder if this plan will go well.

私わたしの選択せんたくは正ただしかったのだろうか。

I wonder if my choice was the right one.

こんなことで諦あきらめていいのだろうか。

Is it really okay to give up over something like this?

Easily confused with

だろうだろう asserts a probability ('probably ~'). Adding か turns it into a question to oneself ('I wonder if ~') — assertion becomes doubt. かなかな is the light, casual 'I wonder' for everyday speech (来くるかな). だろうか is heavier and more deliberative, and works in writing and formal contexts.

See だろうか in real sentences

Jengo shows だろうか the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.

Study it in Jengo

Sources Compiled with reference to A Dictionary of Advanced Japanese Grammar.

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