Provided are: a curable composition having excellent photolithographic properties and resin elution properties; a cured product of the curable composition; and a curing method of the curable composition. The curable composition is characterized by including: (A) at least one selected from the group consisting of a water-soluble polyfunctional (meth)acrylates and water-soluble polyfunctional (meth)acrylamides; and (B) a photosensitive group-containing water-soluble polymer. The water-soluble polyfunctional (meth)acrylates are preferably compounds represented by Formula (I) below, and the water-soluble polyfunctional (meth)acrylamides are preferably compounds represented by Formula (II) below. In Formulae (I) and (II), R1 represents a hydrogen atom, a methyl group, or a halogen atom; X1 represents an alkylene group having 1 to 6 carbon atoms that is optionally substituted with a hydroxy group; A represents an n-valent organic group; R11 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; m represents a number of 1 to 30; n represents a number of 2 to 12; and t represents a number of 2 to 12.