A polymer containing a repeating unit expressed by General Formula (I): n n n n n n n n n n n n where Ar 1 represents a substituted or unsubstituted aromatic hydrocarbon group; Ar 2 and Ar 3 independently represent a divalent group of a substituted or unsubstituted aromatic hydrocarbon group; and R 1 and R 2 each independently represent a hydrogen atom, substituted or unsubstituted alkyl group, or substituted or unsubstituted aromatic hydrocarbon group.