A safety device(1) for a pre-filled syringe(2) comprises a hollow support body (1.2) to retain the pre-filled syringe (2), a retaining collar (1.5) and a rotating collar (1.4) arranged within the support body (1.2). The retaining collar (1.5) is releasably mounted to the support body (1.2). The rotating collar(1.4) is slidable along an axial length of the support body(1.2) and rotatable around a central axis (A) of the safety device (1). The retaining collar (1.5) is movable with respect to the support body (1.2) in a proximal direction when the retaining collar (1.5) is released from being mounted to the support body (1.2) by the rotating collar (1.4).
