604075 A safety device (1) for a pre-filled syringe comprises a hollow support body (1.2) to retain the pre-filled syringe, a retaining collar and a rotating collar arranged within the support body. The retaining collar includes at least one outwardly protruding guide pin (1.4.1) that protrudes through a guide track (1 .2.2) formed into the support body. The guide track comprises an inclined section (1.2.2.1) and an axial section (1.2.2.2) connected therewith. The rotating collar is slidable along an axial length of the support body and rotatable around a central axis (A) of the safety device. The retaining collar is movable with respect to the support body in a proximal direction when the retaining collar is released from being mounted to the support body by the rotating collar driven by a spring.
