The electrical characteristics of a semiconductor device are enhanced. In the package of the semiconductor device, there are encapsulated first and second semiconductor chips with a power MOS-FET formed therein and a third semiconductor chip with a control circuit for controlling their operation formed therein. The bonding pads for source electrode of the first semiconductor chip on the high side are electrically connected to a die pad through a metal plate. The bonding pad for source electrode of the second semiconductor chip on the low side is electrically connected to lead wiring through a metal plate. The metal plate includes a first portion in contact with the bonding pad of the second semiconductor chip, a second portion extended from a short side of the first portion to the lead wiring, and a third portion extended from a long side of the first portion to the lead wiring.