The invention refers to an auto-injector (1) for delivering a liquid medicament, comprising:- an elongate housing (2) arranged to contain a syringe (5) with a hollow injection needle (14) and a stopper (15), wherein the syringe (5) is slidably arranged with respect to the housing (2),- spring means (6) capable of, upon activation:- pushing the needle (14) from a covered position inside the housing (2) into an advanced position for insertion into the injection site,- operating the syringe (5) to inject the dose of medicament (M), and- advancing a needle shroud (3) over the needle (14) for providing needle safety,- activating means arranged to lock and release the spring means (6),wherein the spring means (6) is a single drive spring (6) in the shape of a compression spring grounded distally in the housing (2) and proximally bearing against a thrust collar (7) arranged to transmit load from the spring means (7) via a plunger (11) to the syringe (5) and/or the stopper (13) for needle insertion and injection, wherein the plunger (11) is engageable to the thrust collar (7) for joint axial translation, wherein the plunger (11) is disengageable from the thrust collar (7) on relative rotation so as to allow the thrust collar (7) to be advanced further by the drive spring (6) in order to engage the needle shroud (3) for advancing it over the needle (14).
