A positive resist composition is provided comprising an acid generator, a resin component which generates resin-solubilizing groups under the action of acid so that the resin component becomes soluble in an alkaline developer, at least some resin-solubilizing groups being carboxyl groups, and a compound for activating or condensing a carboxyl group. When processed by the lithography, the resist composition forms a resist pattern having a very high resolution and good mask fidelity.