The present invention relates to a medical injection device (1) for supporting a medical container (90), said medical container comprising a barrel (91) adapted to contain a composition and a needle (94) extending from a distal end of the barrel, wherein the medical injection device comprises: - a body (10) configured to receive at least a part of the medical container (90), - a plunger (20) axially movable relative to the body (10) along an axis (A) of the body, - a needle cover (30) movable relative to the body (10) along the axis (A), the needle cover being configured to move successively between o a storage position wherein the needle cover (30) covers the needle (94), o an injection position wherein the needle cover (30) exposes at least partially the needle (94), o a safety position wherein the needle cover (30) covers the needle (94) and is prevented from moving back to the injection position； wherein the medical injection device further comprises: - a groove (50) comprising a first branch (51 a) and a second branch (51 b) extending from a junction (54) with the first branch (51 a), and - a lug (32) connected to the needle cover (30), the needle cover being configured to move from the storage position to the injection position when the lug (32) is in the first branch (51 a), the needle cover (30) being configured to move from the injection position to the safety position when the lug (32) is in the second branch (51 b)； characterized in that, when the needle cover (30) is in the injection position, the plunger (20) is configured to transition the lug (32) from the first branch (51 a) to the second branch (51 b) when said plunger moves distally.La présente invention concerne un dispositif d'injection médical (1) pour supporter un récipient médical (90), ledit récipient médical comprenant un cylindre (91) conçu pour contenir une composition et une aiguille (94) s'étendant à partir d'une extrémité distale du cylindre, le dispositif d'injection médical comprenant
