A polymer obtained from copolymerization of a recurring unit having a carboxyl group and/or phenolic hydroxyl group substituted with an acid labile group with a methacrylate having a phenolic hydroxyl-bearing pyridine is useful as a base resin in a positive resist composition. The resist composition comprising the polymer is improved in contrast of alkali dissolution rate before and after exposure, acid diffusion control, resolution, and profile and edge roughness of a pattern after exposure.