A polymer comprising recurring units (2) obtained through polymerization of an ester compound of formula (1) is used to form a resist composition. R1 is F or C1-C6 fluoroalkyl, R2 is H or C1-C8 alkyl, R3 is O or C1-C6 alkylene, R4 and R5 each are H or C1-C10 alkyl or fluoroalkyl, and R6 is H or an acid labile group. The resist composition, when processed by ArF lithography, has advantages including improved resolution, transparency, minimal line edge roughness, and etch resistance. The resist composition exhibits better performance when processed by ArF immersion lithography with liquid interposed between a projection lens and a wafer.