To provide a photocurable or thermosetting resin composition which enables alkaline development and is satisfactory in terms of PCT resistance, solder-heat resistance, acid resistance, alkali resistance, adhesion property, electroless gold plating resistance, electric insulation, resistance to crack by heat cycle, film-forming property, warpage resistance, flexibility, folding resistance, etc., and a cured product thereof.

The photocurable or thermosetting resin composition contains (A) a dicarboxylic acid of formula (1) (wherein X is an apliphatic dihydric alcohol residue; and Y is a residue of a dibasic acid, its anhydride, its ester or its halide), (B) a (meth)acrylate compound, (C) a photopolymerization initiator and (D) a compound having at least two cyclic ether groups within a molecule. Preferably, the composition further contains (E) a carboxyl group-containing compound or (F) a curing catalyst, and/or (G) a hardener.