A partly finished product of a semiconductor device includes a resin body encapsulating a semiconductor chip, first and second leads extended outwardly from the resin body, a dam bar connected between said first and second leads, and an excess resin portion protruding from the resin body between the first and second leads and the dam bar. The excess resin portion is cut off at two limited portions, and thereby two groove portions are formed in the excess resin portion. An apparatus for cutting the dam bar includes a punch having a cutting edge for cutting connection portions between the first and second leads and the dam bar and for cutting off the two limited portions of the excess resin portion. Since the cut region of the excess resin portion becomes smaller, a stress imparted to the resin body and/or the semiconductor chip through the excess resin portion can be smaller.