A radiation-sensitive resin composition is provided which exhibits improved resolution, sensitivity, and focal depth allowance (process margin) and can eliminate development residues when forming a resist pattern. The radiation-sensitive resin composition comprises an acid-labile group-containing resin (A) which is insoluble or scarcely soluble in alkali, but becomes alkali soluble by the action of an acid, and a photoacid generator (B), the acid-labile group-containing resin (A) comprises a copolymer prepared by anionic polymerization of monomers including a substituted or unsubstituted styrene and have a terminal shown by the following formula (x). wherein R.sup.14 and R.sup.15 individually represent a hydrogen atom or a linear or branched saturated hydrocarbon group having 1-6 carbon atoms.