Abstract: An alarm tag releasing device is provided for a theft monitoring device. The theft monitoring device has a gate installed in a desired position and producing a theft monitoring region of a predetermined range by transmitting radio waves at a predetermined wavelength. A buzzer tag is attached to a protected item by a built-in lock mechanism so as not to be detached, and an alarm circuit operated by a built-in battery to sound an alarm when the radio waves at the predetermined wavelength are received when the buzzer tags enters the monitoring region, said alarm tag releasing device comprising: an insertion part having a shape corresponding to the outer diameter of the buzzer tag and into which the buzzer tag can be inserted, such that the lock mechanism provided in the buzzer tag is unlocked when the buzzer tag is inserted into the insertion part.