Abstract: Deposition of a hard film of Ti--Si--N composite material on a substrate is carried out by using a source of evaporation possessing a composition of Ti.sub.a Si.sub.b (wherein "a" and "b" stand for atomic percentages respectively falling in the ranges of 75 at %.ltoreq.a.ltoreq.85 at % and 15 at %.ltoreq.b.ltoreq.25 at %, providing a+b=100 at %). Deposition is effected by a sputtering process or ion plating process in an atmosphere of an inert gas containing a nitrogen-containing reaction gas while controlling the feed rate of the reaction gas into a chamber in such a manner that the partial pressure of nitrogen is kept constant or varied continuously or stepwise.