“〜wo moto ni・wo moto ni shite”: Based On / Using 〜 as the Source (for creation/adaptation) [JLPT N2]

Content by NTJ Kuma · Nihongo to Japan editorial team · Updated July 27, 2026

「作者の体験をもとに書かれた小説」 — take it as source material and make something new.

「実話をもとに、映画が作られた」 — take that matter as material and make something new

The line often shown in a film's opening: 「この映画は実話をもとに制作されました」 (this film was made based on a true story) — 「〜をもとに・〜をもとにして」 = based on ～, using ～ as basis, material, blueprint (to create, adapt, produce, calculate), used to express “take something as ‘raw material, blueprint, basis' and produce／create some result from it.” Its focus is “as material to make something.” This guide covers attachment, the noun-modifying 「をもとにした,」 and drawing the line with the near-synonym 「を踏まえて.」

Core: take something as ‘raw material,' process it into a result

「noun ＋ をもとに（して）」 means “using ～ as basis, material, source, produce／create some result”:

• 実話をもとに、小説を書く (using a true story as blueprint, write a novel).
• このデータをもとに、グラフを作成する (using this data as basis, produce a graph).
• 伝説をもとにした物語 (a story based on a legend — 「をもとにした」 modifies the noun).

Feel: “using ～ as material／basis (to make…)” — 「もと (基・元)」 is “basis, material, source,” so 「をもとに」 is “take it as raw material, blueprint, basis, and process, create, calculate a result.” Its key: what precedes is “material, raw stock, blueprint” (a true story・data・legend・experience・survey), and what follows is “the result made from it” (a novel・film・graph・plan・product). It corresponds to “based on ～, using ～ as a blueprint (to make／create).”

Attachment & forms

Examples in use

• 彼の体験をもとに、一本の映画が生まれた。(From his experience as blueprint, a film was born.)
• アンケートの結果をもとに、新商品を開発した。(Based on the survey results, we developed a new product.)
• 古い写真をもとに、当時の街を再現する。(Using old photos as basis, we recreate the town of that time.)
• この理論をもとにして、実験を設計した。(Using this theory as basis, we designed the experiment.)
• 目撃者の証言をもとにした似顔絵が公開された。(A sketch based on witness testimony was released.)

⚠️ Where learners slip up

① The core is ‘take ～ as material／blueprint, produce a result.' 「〜をもとに」's focus is “take what precedes as ‘raw material, stock, blueprint, basis' and process, create, calculate to produce a result.” So there's a clear “material → result” relation across it: what precedes is material (実話・データ・伝説), what follows is “the thing made from it” (映画・グラフ・物語): 昔話をもとに、絵本を作った (using a folk tale as blueprint, made a picture book — the tale is material, the book the result). It corresponds to “based on ～, using ～ as blueprint, from ～ (make).” Test: to say “take something as material／blueprint and produce／create a result” → をもとに. Its biggest difference from 「を踏まえて」: をもとに is “make something using it as material” (output: a work／graph); を踏まえて is “factor it in, then judge” (output: a judgment／action) (see 〈を踏まえて〉).

② Precedes a noun; modify nouns with 「をもとにした.」 Get the attachment right. 「をもとに」 precedes a noun (実話をもとに, データをもとに), before an action. To modify a following noun, use the attributive 「をもとにした」: 事実をもとにした小説 (a novel based on facts) / 事実をもとに小説 (× if a noun follows directly, use した). You can also use the slightly longer 「をもとにして」 (same meaning, a touch more formal). Mnemonic: noun ＋ をもとに (action)／をもとにした (noun).

③ Division of labor with 「を踏まえて／に基づいて」 — don't mix them. All three translate as “based on／according to,” but with different emphases (a frequently-tested N2 set). 「をもとに」 = use ～ as material／basis to create・produce・calculate (take it as raw stock to make a result): 実話をもとに映画を作る (use a true story as material to make a film). 「を踏まえて」 = factor ～ (experience・current situation・opinion) in, then judge (take it into account, see 〈を踏まえて〉): 反省を踏まえて改善する (factor the reflection in and improve). 「に基づいて」 = strictly based on ～ (rules・data・facts, follow without deviation): 規則に基づいて処理する (process by the rules). Test: “take ～ as material to make something” → をもとに; “factor ～ in then judge” → を踏まえて; “strictly follow” → に基づいて. One mnemonic: をもとに = material (make a result), を踏まえて = factor in (then judge), に基づいて = basis (follow it).

🔄 Nuance & comparison: をもとに／を踏まえて／に基づいて／に沿って

💡 How to remember this

「〜をもとに・〜をもとにして」 = based on ～, using ～ as basis, material, blueprint (to create, produce, calculate) — three points: ① the core is “take ～ as material／blueprint, produce a result” — what precedes is material (実話・データ・伝説), what follows the thing made from it (映画・グラフ・物語); ② precedes a noun; modify nouns with 「をもとにした」; ③ division of labor with 「を踏まえて (factor in then judge, see 〈を踏まえて〉)／に基づいて (strictly based on).」 This pattern is super common in creation, research, planning — 「実話をもとに,」 「データをもとに,」 「証言をもとに」 tell you at a glance “this was made from some material.” To express “take something as blueprint／raw stock and produce a result,” 「〜をもとに」 is spot-on. Remember “をもとに = material, を踏まえて = factor in, に基づいて = basis,” and these three won't get mixed up.

❓ FAQ

Q: What's the difference between 「実話をもとに映画を作る」 and 「実話を踏まえて映画を作る」?

The difference is ‘treating it as “creative material” vs as “a factor to weigh.”' 「〜をもとに」 = using ～ as material／blueprint, produce a result: it treats 「実話」 as “the raw material, blueprint of the creation” — the film's content IS “based on this true story, adapting／recreating it”: 実話をもとに映画を作る = “take this true story as blueprint and make (adapt into) a film,” the film's backbone coming from that true story. The focus is “use it as material, produce a work.” 「〜を踏まえて」 = factor ～ in, then make: it treats 「実話」 as “a factor to consider” — not “adapt the true story into a film,” but “factor (some) real situation in, then make a (possibly differently-contented) film”: 実話を踏まえて映画を作る = “factor (that) real situation in, then make a film” (the film isn't necessarily that story, but it's factored in during making). Difference: 「をもとに」 is “use it as blueprint to produce a work” (the work's content = from that material); 「を踏まえて」 is “factor it in, then produce” (treat it as a background factor to weigh). Test: to say “using some story／material as blueprint, produce／adapt into a work” → をもとに; to say “factor some situation in, then do (judge／produce)” → を踏まえて (see 〈を踏まえて〉). E.g. 「事件をもとに小説を書く (write a novel based on the incident — the novel IS about that incident)」 uses をもとに; 「読者の反応を踏まえて続編を書く (factor in reader response, write a sequel — the response is a factor, the sequel's content decided separately)」 uses を踏まえて. One is “material (make something),” the other “factor in (then judge).”

Q: What's the difference between 「をもとに,」 「をもとにして,」 and 「をもとにした」?

They all mean the same (using ～ as basis／material) — the difference is only ‘what follows' and ‘length／formality.' The three are forms of one expression: ① 「〜をもとに」 = tersest, before an action: the commonest form, with an action verb directly after: 実話をもとに映画を作る (make a film based on a true story), データをもとに分析する (analyze based on data). ② 「〜をもとにして」 = adds 「して,」 slightly longer, slightly more formal, before an action: exactly the same meaning as 「をもとに,」 just adding 「して」 (= 「にして」) after 「もとに,」 a touch more weighty and written, with an action still following: 資料をもとにして、計画を立てる (using materials as basis, draw up a plan). Everyday 「をもとに」 suffices; 「をもとにして」 is more for slightly formal writing. ③ 「〜をもとにした」 = attributive form, before a noun: when it modifies a noun, use the attributive 「をもとにした」 (= をもとにして ＋ た): 実話をもとにした映画 (a film based on a true story — modifies 「映画」), 伝説をもとにした物語 (a story based on a legend). Test: before an action → をもとに (／をもとにして, slightly formal); before a noun (modifying) → をもとにした. E.g. 「アンケートをもとに、商品を改良する (improve the product based on the survey — an action follows)」 uses をもとに; 「アンケートをもとにした、改良案 (an improvement plan based on the survey — modifies a noun)」 uses をもとにした. Remember the three together: をもとに (action, terse)／をもとにして (action, slightly formal)／をもとにした (modifying a noun) — check whether an action or a noun follows to know which.

🖊️ Practice Questions (5)

Q1. 「この小説は、作者の体験___書かれた。」(this novel was written based on the author's experience)

(A) に基づいて　(B) をもとに　(C) にしたがって　(D) を踏まえて

Q2. 「民話___作られたアニメが世界中で人気だ。」(the anime made based on folk tales)

(A) に基づいて　(B) をもとに　(C) に従って　(D) を踏まえて

Q3. 「利用者のアンケート___サービスを改善した。」(improved the service using the user survey as material)

(A) をもとに　(B) に基づいて　(C) に反して　(D) について

Q4. Which sentence uses をもとに most naturally?

(A) 法律をもとに、犯人を裁いた。

(B) 地図をもとに、新しい町を設計した。

(C) 証拠をもとに、法律が作られた。

(D) 科学をもとに、判決を下した。

Q5. What is the core difference between 「をもとに」 and 「に基づいて」?

(A) をもとに is colloquial; に基づいて is written.

(B) をもとに means processing/creating from source material; に基づいて means following a standard/rule.

(C) They mean the same and are interchangeable.

(D) をもとに connects only to verbs; に基づいて only to nouns.

Answer Explanations

1. (B) をもとに ── 「作者の体験 (material) をもとに小説を書く (create)」→ をもとに (creating from source material).

2. (B) をもとに ── 「民話 (source material) をもとにアニメが作られた (create)」→ をもとに.

3. (A) をもとに ── 「アンケート (material/opinions) をもとにサービスを改善 (improve)」→ をもとに fits "improving using opinions as material" better than に基づいて.

4. (B) ── 「地図をもとに新しい町を設計した (designed a new town based on the map)」= creating/reshaping from source material → をもとに is most natural. In (A)(D), 法律/証拠 are standards, not material, so に基づいて fits better.

5. (B) ── をもとに = processing/creating from source material or a prototype; に基づいて = acting in accordance with a standard/rule. This is the core difference.