A resist composition contains a base resin, a photoacid generator, and a solvent. The photoacid generator is a sulfonium salt of formula (1). R1 is a monovalent cyclic or bridgedring C3-20, hydrocarbon group, R2 is hydroxyl, nitro, halogen, or a straight, branched or cyclic monovalent C1-15 hydrocarbon group which may contain O, N, S or halogen atom, K− is a non-nucleophilic counter ion, x is equal to 1 or 2, and y is an integer of 0-3. The resist composition is sensitive to ArF excimer laser light, has good sensitivity and resolution, and forms a thick film which is advantageous in etching.