When a user who has a magnetic substance attached paper enters a gate which generates a magnetic field, steep magnetization reversal is produced in the magnetic substance by the magnetic field. As a result, pulse current flows into a detection coil provided in the gate, and a generated waveform signal indicating a characteristic transient response is output to a terminal device. The terminal device calculates correlation coefficients of this waveform and a plurality of stored reference waveforms, additionally calculates an average of the calculated correlation coefficients, and determines whether or not the average is equal to or more than a threshold. When the average is equal to or more than the threshold, the terminal device instructs an imaging device to image a user. When the average is below the threshold, the imaging device is not allowed to image the user.