To form a wiring electrode having excellent contact function, in covering a contact hole formed in an insulting film, a film of a wiring material comprising aluminum or including aluminum as a major component is firstly formed and on top of the film, a film having an element belonging to 12 through 15 groups as a major component is formed and by carrying out a heating treatment at 400.degree. C. for 0.5 through 2 hr in an atmosphere including hydrogen, the wiring material is provided with fluidity and firm contact is realized.