Provided is a semiconductor device including high-frequency interconnect and dummy conductor patterns (second dummy conductor patterns). The dummy conductor patterns are disposed in a interconnect layer different from a interconnect layer in which the high-frequency interconnect is disposed. The dummy conductor patterns are disposed so as to keep away from a region overlapping the high-frequency interconnect in plan view. The semiconductor device further includes dummy conductor patterns (first dummy conductor patterns) in the interconnect layer in which the high-frequency interconnect is disposed.