A reset transistor is prevented from being deteriorated when power-down occurs during a programming operation or an erasing operation. It is made possible to protect the reset transistor as well as other transistors in a circuit to which a high voltage is applied when the power-down occurs during the erasing operation on an EEPROM, because the system is not reset all at once based only on a first reset signal POR of a power-on reset circuit, but is reset based on the first reset signal POR and a low voltage detection signal LD from a low voltage detection circuit so that the reset transistor is not turned on while the high voltage is applied to it.