The automatic injection device comprises an injection spring (24) that is deformable between a compressed state prior to use of the automatic injection device and a relaxed state after injection. It comprises a plunger control member (22) configured to apply a force to a plunger (40) under the action of the injection spring (24) in order to allow the plunger (40) to move in the distal direction of the automatic injection device. The plunger control member (22) bears a stop (118) that is retractable between an active configuration in which it retains the injection spring (24) in the compressed state and a retracted position in which it releases the injection spring (24). The automatic injection device also comprises a locking member (122) for locking the retractable stop (118) in its active configuration, this locking member (122) being able to adopt a locking position in which it applies pressure to the retractable stop (118) to prevent it from adopting its retracted configuration, and an unlocking position in which the retractable stop (118) is released.
