To prevent a current leak in an impurity region surrounding a transistor, in a region where a portion, of a second conductivity type region, extending from a first circuit region side toward a second circuit region side and an element separation film overlap each other in plan view, a field plate and conductive films are provided alternately from the first circuit region side toward the second circuit region side in plan view. Further, in this region, there is a decrease in the potential of the field plate and the potentials of the conductive films from the first circuit region toward the second circuit region. Further, at least one of the conductive films has a potential lower than the potential of the field plate adjacent to the conductive film on the second circuit region side in plan view. Further, this conductive film covers at least a part of the second conductivity type region without space in the extension direction of the second conductivity type region.