A lamp driving apparatus includes a controller, a lamp driver, a lamp voltage detector, a switch and a switching controller. The controller outputs a switch control signal and a lamp driving control signal in response to an instructing signal for instructing a lamp to be turned on and off. The lamp driver supplies an electric power to the lamp in accordance with the lamp driving control signal. The lamp voltage detector detects a voltage applied to the lamp, and outputs a detecting signal showing the applied state of the voltage to the controller. The switch is connected to the lamp driver, a lamp driving power supply line, and a preliminary power supply line, and switches between a first state and a second state selectively. The first state is a state that the electric power for driving the lamp can be supplied to the lamp driver from the lamp driving power supply line The second state is a sate that the electric power for driving the lamp can be supplied to the lamp driver from the preliminary power supply line. The switching controller controls a switching of the switch in accordance with the switch control signal. The controller outputs the switch control signal so as to make the switch to the first state when the instructing signal for instructing the lamp to be turned on. The controller outputs the switch control signal so as to make the switch to the second state in a case that the detecting signal showing an abnormal applied state of the voltage is received from the lamp voltage detector while the controller outputs the lamp driving control signal for turning on the lump.