There has been a problem that micromiaturization causes increase of the resistance of wiring structure and degradation of electron migration resistance and stress migration resistance. The present invention provides a wiring structure of a semiconductor device having a low resistance even when the semiconductor device is microminiaturized, free of electron migration and stress migration, and having a high reliability and a method for manufacturing the same. A semiconductor device having a wiring or a connection plug made of a mixture of a metal and carbon nanotubes berried in a wiring groove or a via hole made in an insulating film on a substrate where a semiconductor chip is fabricated, and its manufacturing method are provided.