Synthesis and the characteristics of an electrically conductings graft copolymer, poly(acrylo-nitrile-co-pyrrolylmethylstyrene)-g-polypyrrole (PANPMS-g-PPy) are reported. It was found that pyrrolyl groups in PANPMS acted as the nuclei for the electrochemical polymerization of PPy. Conductivity of PANPMS-g-PPy was 100 times higher than that of poly(acrylonitrile-co-chloromethylstyrene)/PPy (PANCMS/PPy) composite prepared under the same condition.