A semiconductor device comprising: a semiconductor substrate of a first conductivity type, the semiconductor substrate having a principal surface and a rear surface, being made of silicon carbide, and having, on the principal surface, a device region, a termination region surrounding a circumference of the device region, and a side positioned opposite the device region with respect to the termination region; a first semiconductor region of a second conductivity type that is an opposite conductivity type to the first conductivity type, the first semiconductor region being formed in the semiconductor substrate in the device region; a second semiconductor region formed inside the first semiconductor region and having the first conductivity type; a gate electrode formed between the semiconductor substrate and the second semiconductor region and on the first semiconductor region through a gate insulating film; an annular third semiconductor region (RS1, RS2) formed in the semiconductor substrate in the termination region, having the second conductivity type, and surrounding the circumference of the device region in a plan view; an annular fourth semiconductor region formed inside the third semiconductor region (RS1, RS2), having the second conductivity type, and surrounding the circumference of the device region in a plan view; a first electrode formed over the principal surface of the semiconductor substrate, and connected to the first semiconductor region, the second semiconductor region, and the fourth semiconductor region; and a second electrode formed on the rear surface of the semiconductor substrate, wherein an impurity concentration of the third semiconductor region (RS1, RS2) is lower than that of the fourth semiconductor region, the semiconductor substrate comes in contact with the third semiconductor region (RS1, RS2) in the principal surface, and includes an annular fifth semiconductor region surrounding a circumference of the third semiconductor region (RS1, RS2), and the third semiconductor region (RS1, RS2) between the fourth semiconductor region and the side and the fifth semiconductor region are covered with an oxidation-resistant insulating film (ZM1R) formed on the principal surface, characterized in that: the oxidation-resistant insulating film (ZM1R) is a silicon nitride film or a silicon oxynitride film, and the fourth semiconductor region includes a first region covered with the gate insulating film, and a second region covered with the oxidation-resistant insulating film (ZM1R). a semiconductor substrate of a first conductivity type, the semiconductor substrate having a principal surface and a rear surface, being made of silicon carbide, and having, on the principal surface, a device region, a termination region surrounding a circumference of the device region, and a side positioned opposite the device region with respect to the termination region; a first semiconductor region of a second conductivity type that is an opposite conductivity type to the first conductivity type, the first semiconductor region being formed in the semiconductor substrate in the device region; a second semiconductor region formed inside the first semiconductor region and having the first conductivity type; a gate electrode formed between the semiconductor substrate and the second semiconductor region and on the first semiconductor region through a gate insulating film; an annular third semiconductor region (RS1, RS2) formed in the semiconductor substrate in the termination region, having the second conductivity type, and surrounding the circumference of the device region in a plan view; an annular fourth semiconductor region formed inside the third semiconductor region (RS1, RS2), having the second conductivity type, and surrounding the circumference of the device region in a plan view; a first electrode formed over the principal surface of the semiconductor substrate, and connected to the first semiconductor region, the second semiconductor region, and the fourth semiconductor region; and a second electrode formed on the rear surface of the semiconductor substrate, wherein an impurity concentration of the third semiconductor region (RS1, RS2) is lower than that of the fourth semiconductor region, the semiconductor substrate comes in contact with the third semiconductor region (RS1, RS2) in the principal surface, and includes an annular fifth semiconductor region surrounding a circumference of the third semiconductor region (RS1, RS2), and the third semiconductor region (RS1, RS2) between the fourth semiconductor region and the side and the fifth semiconductor region are covered with an oxidation-resistant insulating film (ZM1R) formed on the principal surface, characterized in that: the oxidation-resistant insulating film (ZM1R) is a silicon nitride film or a silicon oxynitride film, and the fourth semiconductor region includes a first region covered with the gate insulating film, and a second region covered with the oxidation-resistant insulating film (ZM1R). the oxidation-resistant insulating film (ZM1R) is a silicon nitride film or a silicon oxynitride film, and the fourth semiconductor region includes a first region covered with the gate insulating film, and a second region covered with the oxidation-resistant insulating film (ZM1R).