A power-down control circuit utilizes the control signals employed in an active mode operation to operate when a power-down mode entry command is received during an active mode operation. The circuit is simplified requiring less area for devising the control circuit while lowering power consumption. The power-down control circuit in a semiconductor memory device includes at least a clock enable buffer unit, an external clock buffer unit, a latch unit, a control circuit for controlling internally operating clocks employed in active mode operation by using a control signal used in the active mode operation when a power-down mode entry command is received during the active mode operation, and a clock enable generation circuit for outputting clock enable signals for enabling entry to the power-down mode by using the clock control signals, when the external clock pulse signal is low level.