A semiconductor device includes: first and second power transistors connected in parallel with each other and having different saturated currents; and a gate driver driving the first and second power transistors with individual gate voltages, respectively, the gate driver includes a drive circuit receiving an input signal and outputting a drive signal, a first amplifier amplifying the drive signal in accordance with first power voltage and supplying the amplified drive signal to a gate of the first power transistor, and a second amplifier amplifying the drive signal in accordance with second power voltage different from the first power voltage and supplying the amplified drive signal to a gate of the second power transistor.