Abstract: A fastening device including sleeves (2, 6) for absorbing forces, and a rotor blade (10) equipped with such a device for fastening to a hub (23). The device comprises an inner metallic sleeve (2) having a cylindrical central bore (4) and having a frusto-conical outer lateral face which is pressed coaxially and is affixed in the frusto-conical inner bore of an outer sleeve (6) provided with a slot (9) along one of its generatrices, and fitted into a recess delimited in the blade root (10) by a loop (12a) formed of bands (21) of rovings of the spar of the blade. The fitting of the two sleeves into one another involves a deformation by radial expansion of the outer sleeve (6), which adapts itself to the diameter of the recess provided in the composite materials of the blade root. The invention applies to helicopter rotor blades.