Polymerizable ester compounds having formula (1) are novel wherein R1 is H, F, methyl or trifluoromethyl, R2 is an acid labile group, Aa is a divalent hydrocarbon group which may be separated by —O— or —C(═O)—, and k1 is 0 or 1. They are useful as monomers to produce polymers which are transparent to radiation ≦500 nm. Radiation-sensitive resist compositions comprising the polymers as base resin exhibit excellent developed properties.