A method of manufacturing a silicon carbide semiconductor device includes forming on a front surface of a silicon carbide substrate of a first conductivity type, a silicon carbide layer of the first conductivity type of a lower concentration; selectively forming a region of a second conductivity type in a surface portion of the silicon carbide layer; selectively forming a source region of the first conductivity type in the region; forming a source electrode electrically connected to the source region; forming a gate insulating film on a surface of the region between the silicon carbide layer and the source region; forming a gate electrode on the gate insulating film; forming a drain electrode on a rear surface of the substrate; forming metal wiring comprising aluminum for the device, the metal wiring being connected to the source electrode; and performing low temperature nitrogen annealing after the metal wiring is formed.