To provide a loss preventing device which is so constituted that a carried article like spectacles or a key holder may react to inform a user of the existence of itself only at the time of user's intentional search for the carried article.

A small-sized microphone 102 which receives a radio search signal of an electric wave, an ultrasonic wave or the like, a processing circuit 106 which excites a response signal transmission means which generates light and/or an acoustic wave in response to the output of this small-sized microphone 102, a light emitting element 110 and/or a speaker 104 which generate light and/or an acoustic wave by excitation of this processing circuit 106, and a small-sized power source 108 which supplies energy to the processing circuit 106 and the light emitting element 110 and/or the speaker 104 are incorporated as part of the carried article like spectacles or a key holder, and a switch to transmit the radio search signal to the carried article is provided separately from the carried article.