Disclosed is a positive photosensitive insulating resin composition characterized by containing a copolymer (A) composed of 10-99 mol% of a structural unit (A1) represented by the general formula (1) below and 90-1 mol% of a structural unit (A2) represented by the general formula (2) below; a compound (B) having a quinonediazide group; at least one compound (C) selected from the group consisting of aromatic compounds (C1) containing a methylol group and/or an alkoxymethyl group (excluding aromatic compounds containing an amino group), aromatic aldehyde compounds (C2), aliphatic aldehyde compounds (C3), alkyl etherified amino group-containing compounds (C4) and epoxy group-containing compounds (C5); a solvent (D); and an adhesion improver (E). Also disclosed is a cured product of such a positive photosensitive insulating resin composition. (In the formulae, Ra and Rc respectively represent an alkyl group having 1-4 carbon atoms, an alkoxy group or an aryl group; Rb and Rd respectively represent a hydrogen atom or a methyl group; n represents an integer of 0-3; and m represents an integer of 1-3.) The cured product is excellent in various characteristics such as resolution, electrical insulation, thermal shock resistance and adhesiveness.