A charging system configured for reducing a leakage current may include an on board charger (OBC) receiving an alternating current (AC) power supplied from an external source to charge a vehicle battery with the AC power; at least an electric component connected to an output end portion of the OBC; at least a switch selectively connecting the electric component to or from a ground; and a controller connected to the at least a switch and reducing the leakage current flowing to the ground by controlling the switch connected to the electric component depending on whether or not the vehicle battery is charged with the AC power.