The proposed device comprises chain links alternately connected to upper fastening plates and to lower fastening plates. These plates comprise fastening claws of which some are arranged on the front and/or rear edges of the plates and others inside the surface of the plates. Stops are provided for blocking the chain links along the edge of the end of a conveyor belt. Another series of similar chain links are placed against the other end of the conveyor belt. The two series of chain links and plates are braced against the upper and lower sides of the respective conveyor belt ends, the claws fastening them to these ends. A connecting rod is then fitted into the chain links of the two pre-interleaved series, bringing together the conveyor belt ends in the process.