Improvement in the reliability of a semiconductor device is aimed at. By heating a lead frame, after preparing a lead frame with a tape, until a resin molding is performed, at the temperature 160 to 300° C. (preferably 180 to 300° C.) for a total of more than 2 minutes in the atmosphere which has oxygen, crosslinkage density becoming high in resin of adhesives, a low molecular compound volatilizes and jumps out outside, therefore as a result, since a low molecular compound does not remain in resin of adhesives, the generation of copper migration can be prevented.