A dropper type regulator of the invention, in which a semiconductor device is connected in series between a DC power supply and a voltage output terminal, extracts a second voltage from the first voltage of the DC power supply; when the driving voltage of the semiconductor device is detected as being larger than a preset first threshold value, the voltage difference occurring between the input and output terminals of the semiconductor device is detected, and when this voltage difference is detected as being larger than a second threshold value, an overload protection circuit performs overload protection.