Monitoring device (30) for monitoring a drive element (12) of a conveyor (1), in which the drive element (12) extends in a conveyance direction. The monitoring device (30) comprises a mechanism (39) attached to the drive element (12) and configured for mechanically monitoring a distance between two predetermined locations of the drive element (12) spaced apart in the conveyance direction. The monitoring device (30) is further configured for triggering an alarm signal in case the monitored distance exceeds a predetermined limit.