A polymer compound comprising a repeating unit having at least one group selected from the group consisting of a blocked isocyanato group and a blocked isothiocyanato group, a repeating unit having at least one group selected from the group consisting of a hydroxy group and a carboxy group and a repeating unit represented by the following formula (1), wherein the content of the repeating unit having at least one group selected from the group consisting of a blocked isocyanato group and a blocked isothiocyanato group in the polymer compound is 1% by mol or more and 30% by mol or less when the total content of all repeating units contained in the above-described polymer compound is taken as 100% by mol: in the formula (1), R2, R2 and R3 each independently represent a hydrogen atom or a methyl group.