A lighting device that is capable of discriminating a type of an external power source device connected from among types of connectable devices without increasing the number of terminals of a connector. A connector is electrically connectable to an external power source device and includes a first terminal for supplying electric power from the external power source device to a main capacitor and a second terminal for discriminating a type of the external power source device. An obtaining unit obtains the information for discriminating the type of the external power source device by comparing a voltage value of a signal input to the second terminal from the external power source device with a predetermined voltage threshold when an attribute of the second terminal is set to an input. A discrimination unit discriminates the type of the external power source device by contrasting the information obtained with information stored.