A radiation-sensitive resin composition which has high transparency to radiation, excelling in basic properties as a resist such as sensitivity, resolution, and pattern shape, and, in particular, exhibiting high resolution performance, excellent DOF and LER, and high resistance to a liquid medium used in liquid immersion lithography is provided. Also provided are a polymer which can be used in the composition, a novel compound useful for synthesizing the polymer, and a method of producing the composition. A radiation-sensitive resin composition having an excellent resistance to a liquid medium can be obtained by using the novel compound shown by the following formula (1),

wherein R 1 represents a methyl group or a hydrogen atom, R 2 , R 3 and R 4 individually represent a substituted or unsubstituted monovalent organic group having 1 to 10 carbon atoms, n is an integer from 0 to 3, A represents a methylene group, a linear or branched alkylene group having 2 to 10 carbon atoms, or an arylene group, and X - represents a counter ion of S + .