A semiconductor light source driving device includes: a switching power supply circuit that converts a voltage across direct current (DC) power supply into a DC output voltage and outputs the DC output voltage to a semiconductor light source; and a light source driving circuit connected in series to the semiconductor light source. The switching power supply circuit includes: a switching circuit; an output capacitor; a controller; and an inductor short circuit. The switching circuit includes: a first switching element for voltage control; a second switching element connected in series to the first switching element; and an inductor connected to a connection point between the first and second switching elements. The inductor short circuit includes a diode and a fourth switching element connected in series to the diode.