A semiconductor memory device is capable of controlling a delay locked loop appropriately based on operation modes, particularly in a fast power-down mode to reduce an amount of current maximumly. The semiconductor memory device includes a delay-locked clock signal generating unit, a mode signal generating unit, and a delay locking control unit. The delay-locked clock signal generating unit performs a delay locking operation on a clock signal, thereby generating a delay-locked clock signal. The mode signal generating unit enables a fast precharge power-down mode signal in a fast precharge power-down mode. The delay locking control unit controls the delay-locked clock signal generating unit to be activated in a predetermined cycle in response to the fast precharge power-down mode signal.