A power supply device may include an insulating DC/DC converter unit including a primary winding and a secondary winding magnetically coupled to the primary winding, and inducing a voltage in the secondary winding in a first direction or a second direction, and a boosting unit. The boosting unit may comprise a first booster boosting the voltage induced in the secondary winding to supply power to a first light emitting diode module, in a first mode in which the voltage is induced in the secondary winding in the first direction, and a second booster boosting the voltage induced in the secondary winding to supply power to a second light emitting diode module, in a second mode in which the voltage is induced in the secondary winding in the second direction.