A semiconductor device 1 includes a substrate 10, a semiconductor chip 20 (first semiconductor chip), semiconductor chips 30 (second semiconductor chips) and a heat sink 40. Semiconductor chips 20 and 30 are mounted on the substrate 10. The level of the top surface of the semiconductor chip 20 on the substrate 10 is lower than the level of the top surface of the semiconductor chip 30. A heat sink 40 is fixed to the semiconductor chip 20. Among the semiconductor chip 20 and the semiconductor chips 30, only above the semiconductor chip 20 is provided with the heat sink 40.