Disclosed is a method of manufacturing a semiconductor device, which comprises the steps of: forming a hydrogen diffusion preventing insulating film covering capacitors; forming a capacitor protecting insulating film on the hydrogen diffusion preventing insulating film; and forming a first insulating film on the capacitor protecting insulating film by a plasma CVD method where, while a high-frequency bias electric power is applied toward the semiconductor substrate, a plasma-generating high frequency electric power is applied to first deposition gas containing oxygen and silicon compound gas. In the method, a condition by which moisture content in the capacitor protecting insulating film becomes less than that in the first insulating film is adopted as a film deposition condition for the capacitor protecting insulating film.