A mechanically fastened permanent or detachable joint between two or more parts (21, 23, 25, 41), at least one of them made of a composite material, preferably carbon fibers impregnated with thermoset resin, with continuous plies from the full-composite area along the joint area (15) and including a metal reinforcement, preferably made of titanium, in the joint area (15), the joint area (15) thickness being increased in the thickness of said reinforcement plus the eventual additional composite plies laid only on the reinforced area. The metal reinforcement may consist of one or more metal foils or sheets (31) interleaved between the composite plies or one or more metal plates (33) embedded between two of the composite plies.