Disclosed is an automatic injector or syringe plunger operator with multiple safety interlocks to allow safe operation by a non-skilled user or operator. The auto-injector (1) comprises a tubular chassis (2), and a carrier subassembly comprising a tubular carrier (7) slidably arranged in the chassis (2). The carrier (7) contains a syringe (3) with a hollow injection needle (4), a drive spring (8) and a plunger (9) for forwarding load of the drive spring (8) to a stopper (6) of the syringe (3). A wrap-over trigger sleeve (12) arranged over the distal end (D) of the auto- injector (1), the trigger sleeve (12) extends at least almost over the whole length of the auto-injector (1), and a control spring (19) is arranged around the carrier (7). A first interlock means (20, 22) for couples a proximal end of the control spring (19) to either the carrier (7) for advancing it for needle insertion or to the chassis (2) for needle retraction. A second interlock means (11, 13, 15) is arranged for releasing the drive spring (8) for injection. A third interlock means (16, 17, 18) is arranged for coupling the chassis (2) to the carrier (7) for joint axial translation relative to the trigger sleeve (12), and a fourth interlock means (21, 25, 26, 28) is arranged for coupling a distal end of the control spring (19) to either the carrier (7) for needle retraction or to the trigger sleeve (12) otherwise.
