NOVELTY - The system has a transformer (130) whose primary side switching circuit (110) supplies electric current through a primary side winding (131) alternately along forward/reverse manner. A secondary side winding (132) of the transformer is equipped with a secondary side switching circuit (120) to supply the electric current alternately along the forward/reverse manner. The primary side switching circuit and the secondary side switching circuit are provided with a switching element pair that is connected with two switching elements (S) i.e. MOSFETs, for performing switching operation parallelly.    USE - Electric power supply system for a vehicle i.e. hybrid vehicle.    ADVANTAGE - The primary side switching circuit and the secondary side switching circuit are provided with the switching element pair that is connected with the two switching elements for performing switching operation parallelly so as to reduce electric current flowing into the switching element at one side of a failure switching element pair, so that overheating of a bidirectional direct current (DC)/DC converter which connects a high voltage battery with an electric motor of an electromagnetic suspension system apparatus can be prevented, and number of current sensors can be reduced, thus improving vehicle performance, and reducing operation cost of the system. The system is provided with an air spring device provided between a lower arm and a vehicle body for supporting weight of the vehicle body while absorbing impact received from a road surface using compressibility of air, so that riding comfort of a passenger can be improved. The electromagnetic suspension system apparatus performs active control so as to improve control stability of a vehicle and avoid suspension stroke problem by using a stopper contact.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic circuit block diagram of a DC/DC converter of an electric power supply system.'(Drawing includes non-English language text)'    Switching elements (S)    Primary side switching circuit (110)    Secondary side switching circuit (120)    Transformer (130)    Primary side winding (131)    Secondary side winding (132)