A power-up signal generating circuit includes a detecting unit configured to output a bias signal having a voltage level corresponding to an external power voltage in response to an internal voltage and a deep power down (DPD) signal; and a signal generating unit configured to generate a power-up signal having a logic level corresponding to the voltage level of the external power voltage in response to the DPD signal and the bias signal, wherein the internal voltage increases during an activation time of the power-up signal to reach a predetermined voltage level after a predetermined time, and maintains a ground voltage level during an inactivation period of the power-up signal.