The invention relates to an autoinjector comprising a lower body (10 1010) that receives a barrel said barrel containing fluid product and comprising a plunger and a needle. The autoinjector comprises: an actuator sleeve (11 1011) which is provided with a contact end intended to come into contact with the user s body and which can be moved between projecting positions and an actuation position said actuator sleeve (11 1011) occupying a first projecting position prior to actuation and a second projecting position following actuation of the autoinjector injection means (5,8 1005, 1008) for injecting the fluid product through the needle when the needle is in the injection position and an injection lock for locking the injection means (5,8 1005,1008). The actuator sleeve (11 1011) is automatically returned to the second projecting position when the user removes the autoinjector from his/her body and the actuator sleeve (11 1011) is then locked in the second projecting position preventing the autoinjector form being actuated again. The autoinjector also comprises an external shell (22 1022) including at least one viewing window (221,222,223 1221) that provides the user with a visual indication of the autoinjector actuation sequences.
