A method for preparing a polymer compound including copolymerizing a monomer (m0-1) and a monomer (m0-2) to obtain a first polymer compound and causing the first polymer compound and an acid component to react with each other to obtain a second polymer compound. In the formulae, R1 and R2 are each a hydrogen atom, an alkyl group having 1 to 5 carbon atoms and a halogenated alkyl group having 1 to 5 carbon atoms, Va01 is a divalent hydrocarbon group which may have an ether bond, na01 is an integer of 0 to 2, Ra10 is a tertiary alkyl ester-type acid dissociable group, Va02 is a divalent linking group containing a heteroatom, or a single bond, Ra07 is a monovalent organic group, na021 is an integer of 0 to 3, Ra20 is an acid dissociable group, and na022 is an integer of 1 to 3.