Abstract: A polymer comprising hydroxystyrene units and tert-alkoxycarbonylstyrene units is prepared by polymerizing an acetal group-blocked hydroxystyrene monomer and a tert-alkoxycarbonylstyrene monomer to form a preliminary polymer, and subjecting the preliminary polymer to selective deblocking reaction of acetal groups in the presence of an acid catalyst. The polymer thus produced has a narrower molecular weight distribution. A resist composition comprising the polymer as a base resin has advantages including a dissolution contrast of resist film, high resolution, exposure latitude, process flexibility, good pattern profile after exposure, and minimized line edge roughness.