Abstract: An antitheft device of the type having a body unit to be attached to an article displayed in a shop for protecting the article against shoplifting. The device includes a transmitter for radiating an AC signal to a particular area, and the body unit which is adapted to receive a signal from the transmitter. The body unit comprises an alarm generator, and a receiving circuit operative to actuate the alarm generator in response to the signal from the transmitter. The transmitter radiates a feeble electromagnetic wave of less than 30 kHz corresponding to the sound range. The fact that the frequency of output from the transmitter is of a low frequency level corresponding to the sound range provides a greater allowance in the receiver for fluctuations in the frequency of signals received and thus good operation stability of the receiver. False alarming due to extraneous radiation is very unlikely to occur, and other components are free from the possibility of malfunctioning.