A resist pattern-insolubilizing resin composition is used in a resist pattern-forming method. The resist pattern-insolubilizing resin composition includes solvent and a resin. The resin includes a first repeating unit that includes a hydroxyl group in its side chain and at least one of a second repeating unit derived from a monomer shown by a following formula (1-1) and a third repeating unit derived from a monomer shown by a following formula (1-2), wherein for example, R1 represents a hydrogen atom, A represents a methylene group, R2 represents a group shown by a following formula (2-1) or a group shown by a following formula (2-2), R3 represents a methylene group, R4 represents a hydrogen atom, and n is 0 or 1, wherein each of R34 represents at least one of a hydrogen atom and a linear or branched alkyl group having 1 to 10 carbon atoms.