A hydroxystyrene/indene/alkoxyisobutoxystyrene copolymer having Mw of 1,000-500,000 is formulated as a base resin to give a resist composition, typically chemically amplified positive resist composition. The composition exhibits a high resolution, a satisfactory resist pattern profile after development, and improved etch resistance and is thus suitable as a micropatterning material for the fabrication of VLSI.