The invention relates to a marker for power line cables or similar comprising a central body (1) provided with several flexible sides (12, 15) that make up a visually observable pattern, which has a longitudinal inner cavity (11) open at the bottom, suitable for the corresponding cable (3) to be introduced into the same, the cable being fastened by means of a preformed spiral (2) with a slightly smaller diameter than that of the cable (3), which winds and/or couples to the central body (1) of the marker, being fastened to the cable (3) by the winding and elastic deformation of the coils thereof. The markers are mounted on the cable (3) before the installation thereof on the corresponding overhead power line, passing the markers in an unimpeded fashion through the pulleys (8) used in the subsequent mounting of the same.
