Abstract: An individual monitoring device is carried by a person whose movements are to be monitored. The monitoring device comprises a displacement detector arranged to supply a continuously variable signal dependent on the positional changes of the device, signal processing circuit receiving the signal and at least one alarm device operatively connected to the signal processing circuit to provide an alarm in the absence for longer than a predetermined time of a signal due to the monitored person's "normal" movements. The signal processing means comprises a band pass filter for receiving the signal supplied by the displacement detector. The pass band of the filter only allows signals to pass which are due to changes in position of the device consequent upon the monitored person's normal movement.