～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.
Structure
[Noun] + をもとに（して）
Examples
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.
• 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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