A device (1) for connecting bar ends (2'), comprising a hollow body (10) having an internal cavity (12) with at least one bar insertion opening (14) and a longitudinal axis extending through the at least one insertion opening (14), and a plurality of radially-adjustable clamping elements (16), wherein the device further comprises at least one locking element (18) movably arranged inside the hollow body, the internal cavity (12) of said body comprises at least one slope (12') that is inclined relative to the longitudinal axis of said body (10), and said at least one locking element (18) each comprises an inclined face (18') that matches the profile of said at least one slope (12') and a gripping face (18'') having at least one protrusion.