A polymer compound comprising a repeating unit of the following formula (1) and a repeating unit of the following formula (2) and having a polystyrene-reduced number-average molecular weight of 10.sup.3 to 10.sup.8: (wherein, Ar.sup.1 and Ar.sup.2 represent each independently a tri-valent aromatic hydrocarbon group or a tri-valent heterocyclic group, X.sup.1 and X.sup.2 represent each independently O, S, C(.dbd.O), S(.dbd.O), SO.sub.2 or the like, and X.sup.1 and X.sup.2 are not identical. Y represents O, S, and R.sup.9 represents a halogen atom, alkyl group, alkyloxy group or the like. m represents 0 or 1, and n represents an integer from 1 to 6. o represents an integer from 1 to 6, and p represents an integer from 0 to 2.).