A semiconductor device includes an I/O circuit configured to be supplied with a first voltage, a second voltage higher than the first voltage, and a third voltage higher than the second voltage, and to receive an input signal based on the first voltage. The I/O circuit includes an enabler circuit configured to be supplied with the second voltage, and to generate a first signal based on the second voltage, and a first level shifter circuit coupled to the enabler circuit, and configured to, based on the first signal, level-shift a signal based on the second voltage to a signal based on the third voltage.