基本の説明Overview
「彼はどこに住んでいますか」のような疑問文を、I know 〜（〜を知っている）や Can you tell me 〜（〜を教えてくれますか）のような文の中に組み込むことがあります。このように、疑問文が文の一部（名詞のかたまり）になったものを間接疑問文と呼びます。A question such as “Where does he live?” can be folded into a larger sentence like I know ~ (“I know …”) or Can you tell me ~ (“Can you tell me …?”). A question that has become part of a sentence, working like a noun, is called an indirect question.
組み込まれた疑問文は、もう質問ではなく「文の一部」なので、疑問文の語順（動詞 + 主語）にはしません。〈疑問詞 + 主語 + 動詞〉という普通の文の語順になります。また、do / does / did は使わず、動詞を主語や時制に合わせて変化させます（Where does he live? → where he lives）。The folded-in question is no longer a question but a part of the sentence, so it does not keep question word order (verb + subject). It uses ordinary word order: question word + subject + verb. Do not use do / does / did either; conjugate the verb for the subject and tense instead (Where does he live? → where he lives).
疑問詞のない疑問文（Yes / No でこたえる疑問文）を組み込むときは、疑問詞の代わりに if か whether（〜かどうか）を使います。文全体が質問なのか、ふつうの文なのかは、主節（I know など）で決まります。Do you know 〜? なら文末は「?」、I know 〜. なら「.」です。To fold in a yes/no question, which has no question word, use if or whether (“whether or not”) instead. Whether the whole sentence is a question is decided by the main clause (I know…): Do you know ~? ends with “?”, while I know ~. ends with “.”.
| もとの疑問文Original question | 間接疑問文Indirect question |
|---|---|
| Where does he live? | I know where he lives. |
| What is this? | Tell me what this is. |
| Is she busy? | I wonder if she is busy. |
| Who broke the window? | I know who broke the window. |
…+疑問詞+主語+動詞 〜. ／ …+if[whether]+主語+動詞 〜.… + question word + subject + verb ~. / … + if[whether] + subject + verb ~.do / does は使わず、動詞を主語に合わせて変化させる点に注意。疑問詞が主語のときは、もともと〈疑問詞 + 動詞〉の順なので語順は変わらない。Note: don't use do / does — just conjugate the verb to match the subject. When the question word is itself the subject, the order is already question word + verb, so nothing changes.
なお、主節の動詞が過去形（I didn't know 〜 など）のときは、組み込まれた部分の時制も過去形にそろえるのがふつうです。また、Do you think 〜? のように think / believe / guess などがあるときは、疑問詞を文の先頭に出します（Where do you think he lives?）。When the main verb is in the past (I didn't know ~), the folded-in part is normally in the past too. And with verbs like think, believe or guess, as in Do you think ~?, the question word moves to the front of the whole sentence (Where do you think he lives?).
例文で確認Example sentences
① 疑問詞 + 主語 + 動詞1. Question word + subject + verb
I don't know where he lives.
私は彼がどこに住んでいるか知りません。
Where does he live? が文の中に組み込まれた形。does は消え、live が lives になる。This is “Where does he live?” folded into the sentence. does disappears and live becomes lives.
Can you tell me what time it is?
今何時か教えてもらえますか。
What time is it? の is が it のあとに移動する。In What time is it?, the verb is moves after it.
Do you know when the store opens?
その店がいつ開くか知っていますか。
when + 主語 + 動詞。when + subject + verb.
I can't remember why she was angry.
私は彼女がなぜ怒っていたのか思い出せません。
Why was she angry? の was が she のあとに来る。In Why was she angry?, was moves after she.
Could you tell me how I can get to the station?
駅へはどう行けばよいか教えていただけますか。
How can I get ...? の can と I が入れかわる。Could you tell me 〜? はていねいな頼み方。In How can I get…?, can and I swap places. Could you tell me ~? is a polite request.
Tell me how old your brother is.
あなたのお兄さん（弟さん）が何歳か教えてください。
How old is your brother? の is が最後に来る。how old のように「疑問詞 + 形容詞」はひとかたまりで前に置く。In How old is your brother?, is moves to the end. A phrase like how old stays together at the front.
② do / does / did が消えて動詞が変化する2. do / does / did disappear and the verb changes
I know what Mika wants for her birthday.
私はミカが誕生日に何をほしがっているか知っています。
What does Mika want? → does が消え、want が wants に。What does Mika want? → does disappears and want becomes wants.
Do you know where Tom bought that bag?
トムがそのかばんをどこで買ったか知っていますか。
Where did Tom buy ...? → did が消え、buy が過去形 bought に。Where did Tom buy…? → did disappears and buy becomes the past bought.
I asked him what he had for lunch.
私は彼に昼食に何を食べたのかたずねました。
What did you have ...? → did が消え、have が過去形 had に。What did you have…? → did disappears and have becomes the past had.
Tell me how many dogs you have.
あなたが犬を何匹かっているか教えてください。
how many dogs（疑問詞のかたまり）のあとに 主語 + 動詞 が続く。The phrase how many dogs comes first, followed by subject + verb.
③ 疑問詞が主語のとき3. When the question word is the subject
Do you know who wrote this book?
誰がこの本を書いたか知っていますか。
疑問詞 who が主語なので、語順は変わらない（who + 動詞）。The question word who is the subject, so the order stays: who + verb.
Do you know what happened?
何が起こったか知っていますか。
What happened? の what が主語。そのまま組み込む。In What happened?, what is the subject, so it is folded in as it is.
Do you know who is coming to the party?
だれがパーティーに来るか知っていますか。
who is coming は〈疑問詞(主語) + 動詞〉のまま。who is coming keeps the order question word (subject) + verb.
④ if / whether（〜かどうか）4. if / whether (“whether or not”)
I wonder if she will come.
彼女が来るかどうか私は気になります。
Yes / No 疑問文は if（〜かどうか）でつなぐ。A yes/no question is linked with if (“whether”).
I don't know whether he likes sushi or not.
私は彼がすしを好きかどうか知りません。
whether 〜 or not の形もよく使う。The pattern whether ~ or not is also common.
Can you tell me if this bus goes to the museum?
このバスが美術館へ行くかどうか教えてもらえますか。
Does this bus go ...? → does が消え、go が goes に。Does this bus go…? → does disappears and go becomes goes.
Please check whether the door is locked.
ドアにかぎがかかっているかどうか確かめてください。
〈whether + 主語 + 動詞〉は、check の目的語になるかたまり。whether + subject + verb works as the object of check.
It depends on whether it rains tomorrow.
それは明日雨が降るかどうかしだいです。
前置詞（on）のあとには if ではなく whether を使う。After a preposition (on), use whether, not if.
⑤ 主節が過去・疑問詞を文の先頭に出す形5. Past main verbs, and moving the question word to the front
I didn't know where Ken lived.
私はケンがどこに住んでいるのか知りませんでした。
主節が過去形なので、組み込まれた部分も過去形にそろえる。The main verb is past, so the folded-in part is also in the past.
Where do you think he lives?
あなたは彼がどこに住んでいると思いますか。
think があるときは、疑問詞を文の先頭に出す。Do you think where ...? とは言わない。With think, the question word goes to the front. We do not say Do you think where…?
What do you think this word means?
あなたはこの語がどんな意味だと思いますか。
do you think のあとは〈主語 + 動詞〉の語順。After do you think, the order is subject + verb.
確認クイズQuick check
もとの疑問文を組み込んで、空所に入る語を答えましょう。Fold the original question into the sentence and fill in the blank.
- Where does Tom live? → I don't know where Tom ___.
答えを見るShow the answer
lives — does が消え、動詞が主語（Tom）に合わせて lives になる。does disappears, and the verb becomes lives to match Tom. - What did you buy? → Please tell me what you ___.
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bought — did が消え、buy が過去形 bought になる。did disappears, and buy becomes the past bought. - Is she a teacher? → I don't know ___ she is a teacher.
答えを見るShow the answer
if (whether) — Yes / No 疑問文を組み込むときは if か whether を使う。To fold in a yes/no question, use if or whether. - Who broke the window? → Do you know who ___ the window?
答えを見るShow the answer
broke — 疑問詞 who が主語なので、そのまま who + 動詞（過去形 broke）。who is the subject, so it stays who + verb (past tense broke). - How far is the station? → Can you tell me how far the station ___?
答えを見るShow the answer
is — 主語 the station のあとに is を置く（how far は前に出たまま）。Put is after the subject the station (how far stays at the front). - Do you think + Where does he live? →___ do you think he lives?
答えを見るShow the answer
Where — think があるときは疑問詞（Where）を文の先頭に出す。With think, the question word (Where) goes to the front of the sentence.
おさえておきたいポイントKey points
- 疑問文を文の一部に組み込むとき、語順は〈疑問詞 + 主語 + 動詞〉の普通の文の語順になるWhen a question is folded into a sentence, the word order becomes the ordinary one: question word + subject + verb
- do / does / did は使わず、動詞そのものを主語と時制に合わせて変化させる（does live → lives、did buy → bought）Do not use do / does / did; conjugate the verb itself for the subject and tense (does live → lives, did buy → bought)
- Yes / No でこたえる疑問文を組み込むときは if / whether（〜かどうか）を使う。前置詞のあとや whether … or not の形では whether を使うFor a yes/no question use if / whether (“whether or not”). Use whether after a preposition or in the pattern whether … or not
- 疑問詞が主語のとき（who wrote / what happened など）は、語順は変わらないWhen the question word is the subject (who wrote / what happened), the order does not change
- 文末の記号は主節で決まる。Do you know 〜? なら「?」、I know 〜. なら「.」The end punctuation depends on the main clause: Do you know ~? takes “?”, I know ~. takes “.”
- think / believe / guess などがあるときは、疑問詞を文の先頭に出す（Where do you think he lives?）。主節が過去なら、中の時制も過去にそろえるWith think / believe / guess, the question word goes to the front (Where do you think he lives?). If the main verb is past, the verb inside is also past
よくある間違いCommon mistake："I don't know where does he live." ✗ → "I don't know where he lives." ✓ 組み込んだ疑問文は普通の語順にします。does は不要で、live は lives に変わります。"I don't know where does he live." ✗ → "I don't know where he lives." ✓ Use ordinary word order in the folded-in question. No does is needed, and live becomes lives.
よくある間違いCommon mistake："Do you know what is his name?" ✗ → "Do you know what his name is?" ✓ 主語 his name のあとに is を置きます。"Do you know what is his name?" ✗ → "Do you know what his name is?" ✓ Put is after the subject his name.
よくある間違いCommon mistake："Do you think where he lives?" ✗ → "Where do you think he lives?" ✓ think があるときは、疑問詞を文の先頭に出します。"Do you think where he lives?" ✗ → "Where do you think he lives?" ✓ With think, move the question word to the front of the sentence.