The electronically conductive copolymer of PSPMS-g-PPy (poly(styrene-co-pyrrolylmethylstyrene)-g-polypyrrole) was synthesized by the electrochemical method. In this copolymerization, a processable polymer film that has pyrrole moiety in its backbone was used as a copolymer precursor. The precursor was obtained by modifying PSCMS (poly(styrene-co-chloromethylstyrene)) with potassium pyrrole. H-1 NMR spectroscopic analysis indicated that 4.7% of the styrene units in the precursor have pyrrole substituents. Electrolysis of the spin-coated precursor film on platinum electrodes showed optimum copolymerization in a mixture electrolyte consisting of acetonitrile, dichloromethane (80:20 by volume), 0.1 M pyrrole, and 0.1M lithium perchlorate. Constant potential electrolysis showed that pyrrole groups in the precursor were oxidized to form PPy; that is, they acted as grafting centers at which the PPB grew. SEM results and conductivity measurements supported the formation process of PPy copolymer. The maximum conductivity of the final products was in the range of 10(-2) S/cm.