The present invention is a high voltage device system mounted on a railcar and includes a plurality of high voltage devices to which high-voltage electric power from an overhead contact line is supplied, a plurality of high-voltage cables configured to connect the high voltage devices with each other, and a joint device to which the high-voltage cables are connected. The high-voltage cables respectively include cable connector portions at tip end portions thereof, and each of the cable connector portions includes a base tubular portion configured to cover the high-voltage cable and a fit tubular portion extending from the base tubular portion in a direction substantially perpendicular to a longitudinal direction of the high-voltage cable. The joint device includes joint connector portions, each of which is fitted to the fit tubular portion of the cable connector portion to be connected to the high-voltage cable.