The present invention (A) (a) to the repeating unit (II) represented by the general formula (1) repeat unit (I), or a repeating unit (I) and to the formula 1, Formula 2 represented by and (b) It has a carbon-carbon double bond of two or more, at the same time to be decomposed by the action of an acid formula (III) or a monomer having at least one divalent group of the formula (4), each carbon-polymerizable carbon-carbon double bonds is the divalent the carbon of the monomer having a structure linked via a group-copolymer containing a repeating unit (III) obtained carbon-carbon double bond is cleaved, and (B) a radiation sensitive acid generator It relates to a radiation-sensitive resin composition characterized in that it contains a. (In the formula, And A and B are independently from each other is dissociated in the presence of a hydrogen atom or represents an acid-dissociable organic acid having a carbon number of 20 or less to generate acidic functional groups, A and B is at least one of the acid-dissociable organic group, X and Y represent a hydrogen atom or said alkyl group having a carbon number of 1 to 4 independently of each other, n is 0 or 1.) (In the formula, R ¹ and R ² independently represents an alkyl group having a carbon number of 1 to 5 with each other.) (Wherein, R ³ and R ⁴ independently represents an alkyl group having a carbon number of 1 to 5 with each other.) Thus, by the present invention, a high transparency to radiation, there is provided a dry etching resistance as well as have a sufficient resolution is excellent and pattern shape, sensitivity, a sense of balance excellent characteristics, including the radiation-sensitive resin composition. The radiation-sensitive, acid-generating agent, a chemically amplified resist, dry etching resistance