A control circuit is configured to convert a DC voltage that is outputted from a DC power supply to a square wave voltage by switching the switching element according to a PWM signal having a duty ratio that corresponds to a light modulation level of the light source unit, and cause the square wave voltage to be outputted to the light source unit. The control circuit includes a voltage controller configured to control an operating voltage for operating the switching element such that at least one of a rising time and a falling time of a current that flows through the switching element is 1 microsecond or more.