Abstract: A thermosetting resin composition comprising fine particles of an elastomer component homogeneously dispersed in a thermosetting resin is disclosed. The elastomer component comprises a rubbery copolymer prepared from a monomer mixture capable of producing a copolymer having a glass transition point of 25.degree. C. or lower and containing at least one crosslinking monomer having at least two unsaturated bonds in the molecule in the presence of seed polymer particles which are comprised of a polymer having a glass transition point of 25.degree. C. or lower. The possesses excellent impact resistance, mechanical strength, and adhesive strength. It is suitably used as a sealing material of semiconductors, an adhesive for print circuit boards, a molding material, a paint, and a lining material.