The autoinjector (1) includes: a housing (2) extending along a longitudinal axis A; a needle cover (5) coupled to and axially movable with respect to said housing (2) between a first extended position, a retracted position, and a second extended position in which the needle cover (5) moves back in the distal direction to shield an injection needle; a plunger rod (4) axially movable inside the housing (2) between a storage position and an injection end position; a retainer (8), movable with respect to the plunger rod (4) between a blocking position, in which the retainer (8) blocks the plunger rod (4) in the storage position, and a release position, in which the retainer (8) is moved away from the plunger rod (4) to allow axial displacement of the plunger rod (4) from the storage to the injection end position; a locker (9), movable with respect to the retainer (8) between a locking position, in which the locker (9) locks the retainer (8) in the blocking position, and a release position, in which the locker (9) allows movement of the retainer (8) to the release position, movement of the locker (9) from the locking position to the release position being caused by the needle cover (5) moving from the first extended position to the retracted position; and a controller (7), movable with respect to the housing (2), between a storage position which the controller (7) prevents activation of the autoinjector (1) and an activated position allowing for activation of the autoinjector (1), said controller (7) including a grasping member (73) configured for allowing a user to move the controller (7) from the storage position to the activated position. The locker (9) is connected to the controller (7) such that movement of the controller (7) with respect to the housing (2) between the storage and activated position entails movement of the locker (9) with respect to the housing (2) between a corresponding storage and an activated position. The locker (9) includes a blocking member (96) configured for abutting against a stop (281) of the housing (2) as long as the locker (9) is in the storage position, and the blocking member (96) of the locker (9) is moved away from said stop (281) of the housing (2) when the locker (9) is moved to the activated position.