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JLPT N2Formal Expressions

～をもとに／をもとにして— Based On

をもとに (fuller: をもとにして) means 'based on' or 'using ~ as the basis/material'. It marks the source, foundation, or raw material from which something is created, designed, or judged. Use it when a story, plan, product, or decision is built out of some prior information or material.

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Pro lessonUNIT 61 · FORMAL EXPRESSIONS

Structure · 形

[Noun] + をもとに（して）

Examples · 例文

  • この映画は実話をもとに作られた。

    Kono eiga wa jitsuwa o moto ni tsukurareta.

    This film was made based on a true story.

    をもとに shows 実話 (a true story) is the source material for the film.

  • アンケートの結果をもとにして、新商品を開発した。

    Ankēto no kekka o moto ni shite, shinshōhin o kaihatsu shita.

    Based on the survey results, we developed a new product.

    をもとにして marks the survey results as the basis for the development.

  • 彼の証言をもとに、警察は捜査を進めた。

    Kare no shōgen o moto ni, keisatsu wa sōsa o susumeta.

    Based on his testimony, the police advanced the investigation.

    をもとに treats 証言 (the testimony) as the foundation for the police's actions.

Usage notes · 注意

  • をもとにした + noun modifies a noun: 実話をもとにした映画.
  • Emphasizes source/material, not merely reference — the result grows out of it.
  • Register: neutral to formal; common in writing and reports.

Commonly confused with

The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones ～をもとに／をもとにして is tested against.

vs～に基づいて

に基づいて means 'in accordance with / conforming to' a rule, principle, or data and stresses following it; をもとに stresses using something as raw material to create something new, allowing more freedom.

vs～に沿って

に沿って means 'along / in line with' a guideline or flow; をもとに means the item is the base material something is built from, not a path to follow.

More formal expressions

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