A chemically amplified, positive resist composition comprising an organic solvent, a polymer having acid labile groups, a photoacid generator, a basic compound, and a compound containing at least two allyloxy groups is provided. The resist composition has a high sensitivity, resolution, dry etching resistance and process adaptability, and is improved in the slimming of a pattern film after development with an aqueous base solution. The resist composition is also applicable to the thermal flow process suited for forming a microsize contact hole pattern for the fabrication of VLSI.