Abstract: [Problem] To provide an SiC semiconductor device, with which stabilization of high-temperature operation can be achieved by decreasing mobile ions in a gate insulating film, and a method for manufacturing the SiC semiconductor device. [ Solution Means] A semiconductor device 1 has an MIS structure including an SiC epitaxial layer 3, a gate insulating film 9 and a gate electrode 10 formed on the gate insulating film 9. A gate insulating film 9 includes a silicon oxide film in contact with the SiC epitaxial layer 3. In the MIS structure, an area density QM of positive mobile ions in the gate insulating film 9 is made no more than 1×1012 cm?2.