A positive-tone radiation-sensitive resin composition comprising: (A) a carbazole derivative shown by the following formula (1), (B) a photoacid generator containing a sulfonimide compound and an iodonium salt compound as essential components, and (C) an acid-dissociable group-containing resin which is insoluble or scarcely soluble in alkali, but becomes soluble in alkali when the acid-dissociable group dissociates is disclosed. wherein R1 and R2 are individually halogen atom, methyl, cyano, or nitro group, X is a C1-20 organic group, and h and i are 0-4. The resin composition is useful as a chemically amplified positive-tone resist excelling in focal depth allowance, sensitivity, resolution, pattern profile, and PED stability.