Disclosed are a phenolic hydroxyl group-containing resin which has excellent alkali developing properties and makes it possible to exhibit high heat resistance in a cured product obtained therefrom, a production method therefor, a photosensitive composition, a resist material, a coating film, a curable composition and a cured product thereof, and a resist underlayer film.A phenolic hydroxyl group-containing resin, including a compound (A) having a molecular structure represented by the following Structural Formula (1). (In the formula, R1 represents an alkyl group, an alkoxy group, or an aryl group, R2 represents a hydrogen atom, an alkyl group, or an aryl group, m is an integer of 1 to 3, and n is an integer of 2 to 15. In the case where m is 2 or more, plural R1's may be the same as or different from each other.)