Abstract: A fall prevention safety climbing device for workmen ascending and descending ladders on tall structures comprises a sleeve including a locking pawl adapted for attachment to a workman's safety belt, movable along a continuous supporting guide rail fixed to a ladder and for automatic locking engagement with the supporting rail to arrest a workman's fall. The supporting guide rail is provided at predetermined intervals with notched sections adapted to allow disengagement in a specific safe manner of the otherwise entrapped sleeve and attached climber from the supporting guide rail. Hence, a climber can disembark at the desired platform, or level of the structure to allow another climber to pass on by to another level and thereafter reconnect himself and the attached sleeve to the supporting guide rail.