A semiconductor device that can automatically transition from a standby mode to a deep power down (DPD) mode is provided. The semiconductor device includes a DPD controller supporting the DPD mode and multiple internal circuits. The DPD controller measures a time since a time point of entering the standby mode and generates multiple power down enable signals for further reducing power consumption in the standby mode in response to elapse of a measurement time, so that operations of the multiple internal circuits are stopped in stages.