A conventional one-chip dual MOSFET has a structure in which two chips are arranged side by side and drain electrodes are short-circuited. Therefore, the mounting area thereof is large, and the resistance between the drain electrodes cannot be reduced. Accordingly, there is a limit of reduction in size and thickness of a semiconductor device, which is demanded by the market. A dual MOSFET of the embodiment includes two semiconductor chips (MOSFET) superimposed on each other with drain electrodes thereof directly connected to each other. In the dual MOSFET, the drain electrodes do not need to be led to the outside, and only two gate terminals and two source terminals are used. Accordingly, these four terminals are led out by means of a lead frame or conductive patterns. This allows the device to be reduced in size and to have lower on-resistance.