Abstract: A hard wear-resistant film is formed on a substrate in an atmosphere of an inert gas by using a target of a composition of Al.sub.a Ti.sub.b (wherein "a" and "b" stand for atomic percentages respectively in the ranges of 62 at %.ltoreq.a.ltoreq.85 at % and 15 at %.ltoreq.b.ltoreq.38 at %, providing a+b=100 at %) or Al.sub.c Ta.sub.d (wherein "c" and "d" stand for atomic percentages respectively in the ranges of 60 at %.ltoreq.c.ltoreq.80 at % and 20 at %.ltoreq.d.ltoreq.40 at %, providing c+d=100 at %) and by a sputtering process or ion plating process while varying continuously or stepwise the feed rate of a nitrogen-containing reaction gas into a chamber. The film consequently formed has a composition and structure thereof continuously or stepwise varied from a substantially amorphous metal of a part being in contact with the substrate to an (Al, Ti)N or (Al, Ta)N crystalline ceramic phase with the nitrogen content continuously or stepwise increased in the direction of the surface of the film.