In a semiconductor device by which peripheral circuit sections, such as a semiconductor element, a matching circuit section, a bias circuit section, a capacitor element, are placed on and connected to a substrate, the semiconductor element can be grounded, and the semiconductor device which can make heat radiation characteristics of the semiconductor element satisfactory is provided, without providing a via hole into a semiconductor substrate.It includes: a semiconductor element (2) placed on a substrate (1); peripheral circuit sections (30) and (40) placed on the substrate (1) and connected with the semiconductor element (2); an electrode (30e) provided in the peripheral circuit section (30) and grounded; an electrode (30s) for grounding connected to a metal layer (30m), a metal layer (30m) and a source electrode (2s) of the semiconductor element (2); and an electrode (30d) connected to a gate electrode (2g) of the semiconductor element (2).