PURPOSE: To reduce power consumption in the internal voltage generating device of a DRAM.

CONSTITUTION: This device for supplying a constant voltage Vc to the internal circuit DR of a DRAM which is not operated in a battery backup mode M2 in the state of holding data by an internal battery is provided with plural voltage generating means V1-Vn connected in parallel and generating the constant voltage Vc. In a mode M1 at the time of normal operation, all voltage generating means V1-Vn supply the constant voltage Vc to the internal circuit DR of the DRAM and in the battery backup mode M2, a part or all of the voltage generating means V1-Vn stop to supply the constant voltage Vc to the internal circuit DR of the DRAM.