A process for producing a polymer compound having a double bond in a side chain, wherein a functional group represented by the following formula (1) is subjected to an elimination reaction to form the polymer compound which includes another functional group having the double bond in the side chain thereof represented by the following formula (2): 1 wherein, in the formulae, A1 represents an oxygen atom, a sulfur atom or nullN(R4)null; R1, R2, R3 and R4 each independently represent a hydrogen atom or a monovalent organic group; and X1 and Z1 each represent a group that is removable by the elimination reaction.