「前置詞 + 関係代名詞 which」の使い方！口語ではどうなる？in which 、for which 、to which

「in which」「on which」「at which」といった「前置詞 + 関係代名詞 which」の構造をまとめてみました。特に「代用」と「口語」にフォーカスしつつ、頻度や文脈の情報を明確にしています。

1. 基本の仕組み

• 構造: 「前置詞 + which」は、関係代名詞「which」が先行詞（物や事柄）を修飾し、前置詞が関係性を具体化する。例えば、The house in which I live（私が住む家）では、「which」が「house」を修飾し、「in」が「house」と「I live」の関係性を「の中に」と示している。
• 特徴: フォーマル寄り。口語では「which」を「that」に変えたり、前置詞を文末に移動したり、省略したりする。
• ポイント: 前置詞は動詞や状況との相性で決まる。

2. 前置詞 + Which のパターン一覧

(1) よく使われるパターン（頻度高）

前置詞 + Which	意味・用法	例文	注釈
in which	～の中で	The house in which I live is old.	「中に」を示す。「live」「stay」「work」などと相性良い。
on which	～の上に	The table on which the book lies is new.	「表面上」を示す。「lie」「stand」「rest」などと自然。
at which	～で、～に	The moment at which she smiled was perfect.	場所や時間の「点」を示す。「look」「arrive」「smile」などと合う。
to which	～へ、～に	The city to which I moved is beautiful.	方向や対象。「move」「go」「travel」などと合う。
from which	～から	The village from which he came was small.	起点。「come」「return」「escape」などとセットで多い。
for which	～のために	The reason for which I stayed is clear.	目的や理由。「stay」「wait」「fight」などと合う。
with which	～を使って	The pen with which I wrote this is new.	道具。「write」「cut」「draw」などと合う。
of which	～の、～に関する	The book, the cover of which is red, is mine.	所有や属性。「cover」「part」「title」などと合う。

(2) 頻度が低め・特定の文脈で使われるパターン

前置詞 + Which	意味・用法	例文	注釈
by which	～によって	The method by which we solve this is effective.	手段。技術文書や論文で多用。
through which	～を通じて	The channel through which we communicate is secure.	経路やプロセス。フォーマルな記述向け。
under which	～の下で（条件）	The conditions under which we work are tough.	状況や規則。法律や契約で登場。
during which	～の間に	The period during which I was sick was awful.	時間範囲。フォーマルな時間記述。
against which	～に反対して	The rule against which we fought was unfair.	対立や接触。議論や物理的文脈で稀に。
beyond which	～を超えて	The limit beyond which we can’t go is clear.	限界。哲学的・抽象的話題で使用。

3. 前置詞を文末に置く代用と口語での変化

「前置詞 + which」のフォーマルな形をカジュアルにする方法の一つで、前置詞を文末に移動させたり、さらに「which」を省略して自然な会話調に変化させる。

条件:

• 文をカジュアルにしたい時、特に会話やインフォーマルな文章でフォーマルさを避ける場合。
• 前置詞が動詞と強く結びついている場合（例: “live in” “look at”）で、ネイティブが自然に文末に置く語順を好む時。
• 関係詞節が長く、簡潔にして読み手や聞き手の負担を減らす必要がある時。

(1)

• in which
  • 例: The house in which I live is old.
  • 代用: The house which I live in is old.
  • より口語: The house I live in is old.
  • さらに簡略: My house is old.
• on which
  • 例: The table on which the book lies is new.
  • 代用: The table which the book lies on is new.
  • より口語: The table the book lies on is new.
  • さらに簡略: The table with the book on it is new.
• at which
  • 例: The moment at which she smiled was perfect.
  • 代用: The moment which she smiled at was perfect.
  • より口語: The moment she smiled at was perfect.
  • さらに簡略: When she smiled was perfect.
• to which
  • 例: The city to which I moved is beautiful.
  • 代用: The city which I moved to is beautiful.
  • より口語: The city I moved to is beautiful.
  • さらに簡略: My new city is beautiful.
• from which
  • 例: The village from which he came was small.
  • 代用: The village which he came from was small.
  • より口語: The village he came from was small.
  • さらに簡略: His hometown is small.
• for which
  • 例: The reason for which I stayed is clear.
  • 代用: The reason which I stayed for is clear.
  • より口語: The reason I stayed for is clear.
  • さらに簡略: Why I stayed is clear.
• with which
  • 例: The pen with which I wrote this is new.
  • 代用: The pen which I wrote this with is new.
  • より口語: The pen I wrote this with is new.
  • さらに簡略: The pen I used is new.
• of which
  • 例: The book, the cover of which is red, is mine.
  • 代用: The book whose cover is red is mine.
  • より口語: The book with the red cover is mine.

(2)

• by which
  • 例: The method by which we solve this is effective.
  • 代用: The method which we solve this by is effective.
  • より口語: The method we solve this by is effective.
  • さらに簡略: How we solve this is effective.
• through which
  • 例: The channel through which we communicate is secure.
  • 代用: The channel which we communicate through is secure.
  • より口語: The channel we communicate through is secure.
  • さらに簡略: Our communication channel is secure.
• under which
  • 例: The conditions under which we work are tough.
  • 代用: The conditions which we work under are tough.
  • より口語: The conditions we work under are tough.
  • さらに簡略: Our working conditions are tough.
• during which
  • 例: The period during which I was sick was awful.
  • 代用: The period which I was sick during was awful.
  • より口語: The period I was sick during was awful.
  • さらに簡略: When I was sick was awful.
• against which
  • 例: The rule against which we fought was unfair.
  • 代用: The rule which we fought against was unfair.
  • より口語: The rule we fought against was unfair.
  • さらに簡略: The rule we opposed was unfair.
• beyond which
  • 例: The limit beyond which we can’t go is clear.
  • 代用: The limit which we can’t go beyond is clear.
  • より口語: The limit we can’t go beyond is clear.
  • さらに簡略: Our limit is clear.

4. That での代用

「which」を「that」に置き換え、前置詞を文末に移動させるカジュアルな代用方法。口語的で簡潔さが求められる場面に適する。

条件:

• フォーマルな「前置詞 + which」よりもカジュアルなトーンを好む時、特に会話や日常的な文章で。
• 「that」が制限用法（カンマなしの必須情報）で使われる場合に自然。
• 前置詞と動詞の結びつきが強い表現で、文末移動が違和感ない時。

(1)

• in which
  • 例: The house in which I live is old.
  • “that”で代用: The house that I live in is old.
• on which
  • 例: The table on which the book lies is new.
  • “that”で代用: The table that the book lies on is new.
• at which
  • 例: The moment at which she smiled was perfect.
  • “that”で代用: The moment that she smiled at was perfect.
• to which
  • 例: The city to which I moved is beautiful.
  • “that”で代用: The city that I moved to is beautiful.
• from which
  • 例: The village from which he came was small.
  • “that”で代用: The village that he came from was small.
• for which
  • 例: The reason for which I stayed is clear.
  • “that”で代用: The reason that I stayed for is clear.
• with which
  • 例: The pen with which I wrote this is new.
  • “that”で代用: The pen that I wrote this with is new.
• of which
  • 例: The book, the cover of which is red, is mine.
  • “that”で代用: The book that the cover of is red is mine.（不自然なので通常不可）。

(2)

• by which
  • 例: The method by which we solve this is effective.
  • “that”で代用: The method that we solve this by is effective.
• through which
  • 例: The channel through which we communicate is secure.
  • “that”で代用: The channel that we communicate through is secure.
• under which
  • 例: The conditions under which we work are tough.
  • “that”で代用: The conditions that we work under are tough.
• during which
  • 例: The period during which I was sick was awful.
  • “that”で代用: The period that I was sick during was awful.
• against which
  • 例: The rule against which we fought was unfair.
  • “that”で代用: The rule that we fought against was unfair.
• beyond which
  • 例: The limit beyond which we can’t go is clear.
  • “that”で代用: The limit that we can’t go beyond is clear.

5. 他の関係詞での代用

「前置詞 + which」を「where」「whose」「when」「how」などの関係詞で置き換える方法。先行詞の種類（場所、所有、時間、方法など）に依存し、前置詞を省略して簡潔にする。

条件:

• 先行詞が場所、時間、理由、方法など、特定の関係詞に適合する意味を持つ場合。
• 前置詞のニュアンスが文脈で補えるか、なくても意味が通じる時。
• より自然で簡潔な表現を求める会話やカジュアルな文脈で。

(1) よく使われるパターン（頻度高）

• in which → where（場所）
  • 例: The house in which I live is old.
  • 代用: The house where I live is old.
  • 条件: 先行詞が場所（house, room, cityなど）を指す。「in」の「中にある」を「where」が吸収。
• in which → when（時間）
  • 例: The year in which I was born was 1990.
  • 代用: The year when I was born was 1990.
  • 条件: 先行詞が時間（year, period, timeなど）を指す。「in」の「その中で」を「when」が「その時に」として自然に置き換え。
• on which → where（場所）
  • 例: The table on which the book lies is new.
  • 代用: The table where the book lies is new.
  • 条件: 先行詞が場所（table, shelfなど）で、位置関係が文脈でわかる。「on」のニュアンスが弱まる。
• at which → where（場所）
  • 例: The place at which we met was crowded.
  • 代用: The place where we met was crowded.
  • 条件: 先行詞が場所（place, spot, pointなど）を指す。「at」の「特定の点」が「where」に移行。
• at which → when（時間）
  • 例: The moment at which she smiled was perfect.
  • 代用: The moment when she smiled was perfect.
  • 条件: 先行詞が時間（moment, time, dayなど）を指す。「at」の「特定の点」が「when」に移行。
• to which → where
  • 例: The city to which I moved is beautiful.
  • 代用: The city where I moved is beautiful.
  • 条件: 先行詞が場所（city, townなど）で移動先を示す。「to」の方向性が省略される。
• from which
  • 例: The village from which he came was small.
  • 代用: 「where」などでは直接置き換え不可。「from」の起点が必須。
• for which → why
  • 例: The reason for which I stayed is clear.
  • 代用: The reason why I stayed is clear.
  • 条件: 先行詞が理由（reason, causeなど）を指す。「for」が「why」に簡潔化。
• with which
  • 例: The pen with which I wrote this is new.
  • 代用: 「where」「whose」などでは置き換え不可。「with」の道具が特殊。
• of which → whose
  • 例: The book, the cover of which is red, is mine.
  • 代用: The book whose cover is red is mine.
  • 条件: 所有や部分関係を示す。物にも使える。

(2) 低頻度、限定的、使えないパターン

• on which → when
  • 例: The day on which we met was rainy.
  • 代用: The day when we met was rainy.
  • 条件: 先行詞が時間（day, occasionなど）で、「on」が特定の日を指す場合。「on」の「その上での出来事」が「when」に置き換え可能だが限定的。
• by which → how
  • 例: The method by which we solve this is effective.
  • 代用: The method how we solve this is effective.（やや不自然）。
  • 条件: 先行詞が方法（method, wayなど）を指す。自然には The way we solve this が好まれる。
• through which → where
  • 例: The channel through which we communicate is secure.
  • 代用: The channel where we communicate is secure.
  • 条件: 経路が場所的（channel, pathなど）と解釈可能。「through」が弱まる。
• under which
  • 例: The conditions under which we work are tough.
  • 代用: 「where」「when」などでは置き換え不可。「under」の条件が必須。
• during which → when
  • 例: The period during which I was sick was awful.
  • 代用: The period when I was sick was awful.
  • 条件: 先行詞が時間（period, timeなど）を指す。「during」が「when」に。
• against which
  • 例: The rule against which we fought was unfair.
  • 代用: 「where」「how」などでは置き換え不可。「against」の対立が必須。
• beyond which
  • 例: The limit beyond which we can’t go is clear.
  • 代用: 「where」「when」などでは置き換え不可。「beyond」の「超える」が特殊。

まとめ

• where: 場所を示す「in/on/at/to which」に適用。例: The park in which we played → The park where we played.
• when: 時間を示す「in/at/during/on which」に適用。例: The day at which we met → The day when we met.
• why: 理由を示す「for which」に適用。例: The reason for which he left → The reason why he left.
• how: 方法を示す「by which」に適用（制限的）。例: The way by which we did it → The way how we did it（The way we did it が自然）。
• whose: 所有を示す「of which」に適用。例: The car, the engine of which is broken → The car whose engine is broken.