The present invention addresses the problem of providing: a resin containing phenolic hydroxyl groups which is excellent in terms of developability, heat resistance, and conformability to substrates; a photosensitive composition and a curable composition each containing the resin; and a resist film. The resin containing phenolic hydroxyl groups is obtained by reacting ingredients comprising both a triarylmethane type compound (A) and an aldehyde compound (B) as essential ingredients to obtain a novolac resin intermediate and reacting the intermediate with a C9-24 alkene compound (C). The photosensitive composition and the curable composition each contain this resin. The resist film is provided.
