A baggage management gate including an exciting coil, a detecting coil and signal processing unit. The exciting coil forms an alternating magnetic field in a passage to an area from which manages objects to be carried in or carried out. The detecting coil detects a variation in the alternating magnetic field when magnetization of a magnetic material showing a large Barkhausen effect is reversed in the alternating magnetic field. The signal processing unit determines as to whether the magnetization reversal occurs in the alternating magnetic field due to the large Barkhausen effect or not, based on a signal detected by the detecting coil. The signal processing unit includes amplifier that amplifies the signal detected by the detecting coil with plural different amplification factors and output the amplified signals with each of the plural different amplification factors.