A substrate for printed circuit board, comprising an adhesive layer on a circuit forming plane, said adhesive layer being a cured resin produced by curing a composition comprising an epoxy resin, a synthetic rubber, and a phenol resin, the epoxy resin, the synthetic rubber and the phenol resin constituting three resin components of the composition, a vulcanizing agent, a photosensitive hardener which produces Lewis acid upon irradiation with ultraviolet rays, an inorganic filler powder having hydroxyl groups which release hydroxyl groups upon heating, and an organic solvent, wherein the composition has been cured by being irradiated with ultraviolet rays followed by heating until the composition is cured.