The invention concerns an injection device, comprising an interface (3) for mounting on a syringe body (1), the interface (3) comprising an internal passage delimited by an inner wall (11), a needle (19) and a sheath (8) for receiving said needle (19), said sheath (8) comprising an outer wall (12) provided with a contact portion of said sheath (8) in contact with an attachment portion of the inner wall of the interface (3), characterised in that the contact portion comprises a first bead (16) and in that the attachment portion comprises a second bead (17), the first and second beads (16, 17) each forming a ring protruding respectively on the contact portion and the attachment portion, the first bead (16) being in contact with the second bead (17).
