An overcurrent protection circuit has an output voltage detection resistor for detecting an output voltage. A foldback overcurrent protection circuit detects an output current flowing through an output transistor and controls the output current flowing through the output transistor in accordance with the detected output current. A first logic generating circuit receives an overcurrent detection signal from the foldback overcurrent protection circuit corresponding to the detected output current. A second logic generating circuit receives a detection signal from the output voltage detection resistor corresponding to a decrease in the detected output voltage. An AND circuit receives and processes an overcurrent delay signal generated by the first logic generating circuit and a voltage detection signal generated by the second logic generating circuit. A negative voltage generating circuit receives an output from the AND circuit and outputs a negative voltage to the foldback overcurrent protection circuit to control the output current flowing through the output transistor.