Joining device for seals of the type comprising a U-shaped element 2 for fixing on a frame and a tubular sealing element 3. According to the invention, this device comprises at least one insert constituted of a tab 1 of curved cross-section designed to be placed longitudinally at the bottom of the fixing element so as to be held in abutment between the two branches of the U and to straddle the two contiguous seal ends 2, 22.