A method for manufacturing a semiconductor device comprising forming a titanium or titanium compound film by a CVD method which uses a material gas containing an organic titanium compound of the formula (I) ##STR1## wherein R is a hydrogen atom, a lower alkyl group, a C8-13 condensed polycyclic hydrocarbonyl group or a silyl group which is substituted with a lower alkyl and/or an aryl, and a reduc