The invention relates to a safety device (1) for a syringe (2), the device comprising a protective sheath (20) in which the syringe (2) can slide, said sheath (20) presenting an opening (36) at a distal portion (33), which opening is suitable for allowing the syringe (2) to project beyond the sheath (20). According to the invention, the sheath (20) presents radial resilience at its distal portion (33) suitable for enabling the sheath (20) to receive a cylinder (3, 19) of diameter greater than that of said opening (36).
