A receiver base receives from below a front end portion of a label that is fed forward from a folded-back portion of an release paper and droops forward, so that the label is held in a predetermined forwardly and downwardly inclined posture. The valves provided in the bypass path are housed in the support member. The central unit also calculates a difference between the detected currents and compares the difference with a second predetermined level, thereby detecting failure in the communication wires and stopping activation of the passenger protection device. The computer system electronically connects with and controls the driving mechanism.