A circuit device includes a first conductive plate and a second conductive plate each having a belt-shaped portion arranged side-by-side with each other, a third conductive plate having a belt-shaped portion is arranged side-by-side with and spaced apart from the other side portion of the first conductive plate, a first circuit component having a first terminal connected to the first conductive plate and a second terminal connected to the second conductive plate, a second circuit component having a first terminal connected to the first conductive plate and a second terminal connected to the third conductive plate, a first external connection portion provided at the belt-shaped portion of the first conductive plate, and a second external connection portion provided at the belt-shaped portion of the second conductive plate or a third external connection portion provided at the belt-shaped portion of the third conductive plate.