A power-on reset circuit includes a voltage detector unit to output an electrical signal in response to a power supply voltage received from a power supply terminal, an inverter to output a reset signal according to a level of the electrical signal from the voltage detector unit, a first switch unit to be turned on or off in response to the reset signal from the inverter; a first discharge unit to discharge the electrical signal in response to the power supply voltage from the first switch unit, a second switch unit to be turned on according to a start pulse signal from an external device and to receive the power supply voltage from the power supply terminal, and a second discharge unit to discharge the electrical signal in response to the power supply voltage from the second switch.