Provided is a semiconductor device including a step-down circuit group including multiple step-down circuits that step down an external power supply voltage to a predetermined voltage; multiple functional circuits that require a reset operation upon power-on; and a power-on reset circuit that outputs a reset command to the multiple functional circuits, when an internal power supply voltage supplied from the step-down circuit group exceeds a voltage level necessary for an initialization operation. The multiple step-down circuits of the step-down circuit group are classified into a startup operating step-down circuit group that performs a step-down operation from power-on to supply the internal power supply voltage, and a startup non-operating step-down circuit group that stops operation upon power-on to interrupt supply of the internal power supply voltage. The startup non-operating step-down circuit group includes the multiple step-down circuits sequentially selected from one having a shortest wiring distance from the power-on reset circuit.