Described is an auto-injector (1) for administering a medicament comprising a case (4, 5) arranged to receive a packaged syringe (3) comprising an injection needle (11), wherein the case (4,5) comprises a front case (4) rotatably coupled to a rear case (5), and a drive spring (15) arranged to advance a plunger (16) relative to the packaged syringe (3), and a reset mechanism for the drive spring (15) arranged to retract the plunger (16) and compress the drive spring (15) when the front case (4) is rotated relative to the rear case (5).