There is disclosed a resist composition which comprises, at least, a polymer in which a sulfonium salt having a polymerizable unsaturated bond, a (meth)acrylate having a lactone or a hydroxyl group as an adhesion group, and a (meth)acrylate having an ester substituted with an acid labile group are copolymerized. There can be provided a resist composition with high resolution which has high sensitivity and high resolution to high energy beam, especially to ArF excimer laser, F.sub.2 excimer laser, EUV, X-ray, EB, etc., has reduced line edge roughness, and comprises a polymeric acid generator which has insolubility in water, and sufficient thermal stability and preservation stability.