PROBLEM TO BE SOLVED: To provide a radiation sensitive resin composition for forming a resist coating film which has excellent nano edge roughness, sensitivity and resolution. SOLUTION: The radiation sensitive resin composition contains (A) a resin containing at least one kind selected from a group comprising repeating units represented by general formulae (a-1) to (a-4), and (B) an acid generator represented by a general formula (b). In the formulae (a-1) to (a-4), R 1 is a hydrogen atom or a methyl group, R 2 is a 1-12C straight-chain or branched alkyl group or a 1-12C straight-chain or branched alkoxyl group, k is an integer of 0 to 3, and l is an integer of 0 to 3 (0≤k+l≤5). R 3 is a hydrogen atom or a methyl group, and R 4 is a 1-12C straight-chain or branched alkyl group or a 1-12C straight-chain or branched alkoxyl group; n is an integer of 0 to 3; and m is an integer of 0 to 3 (0≤n+m≤5). R 5 is a hydrogen atom or a methyl group, and R 6 is a 1-12C straight-chain or branched alkyl group or a 1-12C straight-chain or branched alkoxyl group; p is an integer of 0 to 3; and q is an integer of 0 to 3 (0≤p+q≤5). COPYRIGHT: (C)2011,JPO&INPIT