There is provided a semiconductor device supplied with internal power generated by an internal power generation circuit to perform a stable operation and, also, suppress power consumption. A control circuit, a row/column decoder and a sense amplifier are driven by an internal buck voltage. On the other hand, a data path with high power consumption is driven by an external power supply voltage. A level conversion circuit receives an address signal or a command signal having a voltage level of the external power supply voltage, converts the voltage level to the internal buck voltage, and outputs a resultant signal to the control circuit. A level conversion circuit receives a control signal having a voltage level of the internal buck voltage from the control circuit, converts the voltage level to the external power supply voltage, and outputs a resultant signal to the data path.