The piperazinylethylaminocarbonyl-containing butadiene-acrylonitrile copolymer of this invention is a novel substance useful as an adhesive component for adhesive tapes, which tapes are used in the interior of a resin-sealed type semiconductor device. The copolymer has a weight average molecular weight of 10,000-200,000, and is represented by the following general formula (I) and obtained by condensing a carboxyl-containing butadiene-acrylonitrile copolymer having a weight average molecular weight of 10,000-200,000 with N-aminoethylpiperazine in the presence of a phosphite and a pyridine derivative to undergo the amidation. ##STR1## wherein k, m, and n indicate molar proportions, where n is taken as 1, k is a number in the range of 3-175, and m is a number in the range of 0.3-93.