A power supply circuit to supply an internal voltage to an output node includes: a pull-up driver, in response to a result obtained by comparing the internal voltage to a first reference voltage, configured to generate the internal voltage from a power supply voltage, a pull-down driver, in response to a result obtained by comparing the internal voltage to a second reference voltage, configured to discharge the internal voltage, a pull-up drive blocking unit configured to block the pull-up driver from being driven, in response to the result obtained by comparing the internal voltage to the second reference voltage, and a pull-down drive blocking unit configured to block the pull-down driver from being driven, in response to the result obtained by comparing the internal voltage to the first reference voltage.