To surely detect a connection state while reducing a resistance value of resistors for current consumption detection, and to prevent from being affected by wraparound noise when detecting the connection state of an integrated antenna based on consumption of currents flowing into the integrated antenna equipped with a VICS optical transmitting/receiving element.

A current flowing from a device body 2 into an integrated antenna 3 flows through a coil 6. When a pseudo up-link signal is outputted from a VICS (light) signal processing section 17 to check a connection state of the integrate antenna 3, since a large current flows through a transmitting element 26 for optical beacons of the integrated antenna 3, a drop voltage of the coil 6 becomes large. When the drop voltage of the coil 6 is within a prescribed range because of divided voltages of resistors 8, 9, an antenna connection detection section 10 determines that the integrated antenna 3 is normal. In this case, since a large current flows into the coil 6, a coil having small impedance is available as the coil 6.