To improve the directivity and the sensitivity difference of the electromagnetic field in a resonance tag detection area with the devise of the forms of a transmission antenna and a reception antenna.

The transmission antenna 1 which is connected to a transmission means 6, has plural independent loops in a common plane and has an amplifier 7 that is electromagnetically driven so that the respective loops have opposite phases by 180 degrees and a reception antenna 3 which is connected to a reception means 8, has plural independent loops whose number differs from that of the loops in the transmission antenna 1, in the common plane and has an amplifier 7 which is electromagnetically driven so that the respective loops have the opposite phases by 180 degrees are arranged on both sides of a path where a resonance tag passes for detection at prescribed interval. The transmission antenna 1 and the reception antenna 3 have mutual electromagnetic connection and the antennas 1 and 3 have the effective whole loop area of the opposite phases, which is almost equal to that of the effective whole loop area of the prescribed phase.