Protection device (1) intended to cover at least partially the needle (2) of an injection device, at least said protection device (1) comprising: - a support (3) provided with fixing means (9) intended to secure said protection device (1) to an injection device, - a sheath (4) comprising a distal end (15) intended to come into contact with an injection surface and provided with an orifice intended to allow the said needle passes, said sheath (4) being arranged so that it can move axially in translation relative to said support (3) from a first position known as the storage position, in which the distal end of said sheath (4) is at a distance 11 from said fixing means, to a second position known as the injection position, in which the distal end of said cover (4) is at a distance 12 from said fixing means ation, and to a third position known as the protection position, in which the distal end of said sheath (4) is at a distance 13 from said fixing means, said distances 11 and 13 being greater than said distance 12, - first return means (14) for returning said sheath (4) at least from its injection position to its protection position, - at least one pin (6), directly and at least elastically, longitudinally coupled to said support (3) or said cover (4) and housed in a circulation corridor (10) provided respectively in said cover (4) or in said support (3), said circulation corridor (10) which forms more or less a U, whose branches respectively define a first section (11) taken by said pin (6) as said sheath (4) moves from its storage position to its injection position and a second section (12) taken by said pin (6) when said sleeve ( 4) passes from its injection position to its protection position, said pin (6) being designed to be laterally movable, - first means (5, 21； 39, 34, 35) of safety, being at least part of them elastically deformable, said first security means (5, 21； 39, 36, 34, 35) being arranged in such a way as to prevent said pin (6) return from said s
