A safety device for a pre-filled syringe, comprising - a tubular support body (1.2) to retain therein the pre-filled syringe with a guide track (1.2.2) formed into the support body (1.2), whereas the guide track (1.2.2) comprises an inclined section (1.2.2.1) and an axial section (1.2.2.2) connected therewith, - a hollow outer body (1.3) having an open distal end accommodating a proximal end of the support body(1.2), the outer body (1.3) being slidable relative to the support body (1.2), - a needle shield (1.1) received within an open distal end of the support body (1.2), - a retaining collar (1.5) releasably mounted to the proximal end of the support body (1.2) and mounted to the prefilled syringe and - a rotating collar (1.4) arranged within the support body (1.2) to be moved between an initial or an proximal position (PI, PP) adjacent the retaining collar (1.5) and a distal position, the rotating collar (1.4) comprising - a central opening for the reception of the prefilled syringe configured such that the rotating collar (1.4) can be moved along a pre-filled syringe barrel (2.3) and rotated relative to the pre-filled syringe and - at least one outwardly protruding guide pin (1.4.1) that protrudes through a guide track (1.2.2) formed into the support body (1.2.2), characterized in that the safety device further comprising - a spring (1.6) being arranged within the support body (1.4) between the needle shield (1.1) and the rotating collar (1.4) in an at least partially energized state, so that the needle shield (1.1) and the rotating collar (1.4) are biased away from each other and - a guide rail (1.3.3) formed into the inner surface of the outer body (1.3) and abutting the guide pin (1.4.1) to move and guide the guide pin (1.4.1) along the guide track (1.2.2) during injection, whereby the rotating collar (1.4) rotates around a central axis of the safety device and is pushed distally against the biasing force of the spring (1.6) towards the distal position until the guide pin (1.4.1) reaches the distal end of the axial section (1.2.2.2) of the guide track (1.2.2) at the end of the injection stroke, and wherein upon removal of the injection device from the injection site, the spring (1.6) moves the needle shield (1.1) distally and moves the rotating collar (1.4) in the proximal direction towards the proximal position whereby the rotation collar (1.4) urges the retaining collar (1.5) in the proximal direction so as to release the retaining collar (1.5) from being mounted within the support body (1.2) and to push it further in the proximal direction, whereby the pre-filled syringe mounted to the retaining collar (1.5) is retracted. - a tubular support body (1.2) to retain therein the pre-filled syringe with a guide track (1.2.2) formed into the support body (1.2), whereas the guide track (1.2.2) comprises an inclined section (1.2.2.1) and an axial section (1.2.2.2) connected therewith, - a hollow outer body (1.3) having an open distal end accommodating a proximal end of the support body(1.2), the outer body (1.3) being slidable relative to the support body (1.2), - a needle shield (1.1) received within an open distal end of the support body (1.2), - a retaining collar (1.5) releasably mounted to the proximal end of the support body (1.2) and mounted to the prefilled syringe and - a rotating collar (1.4) arranged within the support body (1.2) to be moved between an initial or an proximal position (PI, PP) adjacent the retaining collar (1.5) and a distal position, the rotating collar (1.4) comprising - a central opening for the reception of the prefilled syringe configured such that the rotating collar (1.4) can be moved along a pre-filled syringe barrel (2.3) and rotated relative to the pre-filled syringe and - at least one outwardly protruding guide pin (1.4.1) that protrudes through a guide track (1.2.2) formed into the support body (1.2.2), characterized in that the safety device further comprising - a central opening for the reception of the prefilled syringe configured such that the rotating collar (1.4) can be moved along a pre-filled syringe barrel (2.3) and rotated relative to the pre-filled syringe and - at least one outwardly protruding guide pin (1.4.1) that protrudes through a guide track (1.2.2) formed into the support body (1.2.2), characterized in that the safety device further comprising - a spring (1.6) being arranged within the support body (1.4) between the needle shield (1.1) and the rotating collar (1.4) in an at least partially energized state, so that the needle shield (1.1) and the rotating collar (1.4) are biased away from each other and - a guide rail (1.3.3) formed into the inner surface of the outer body (1.3) and abutting the guide pin (1.4.1) to move and guide the guide pin (1.4.1) along the guide track (1.2.2) during injection, whereby the rotating collar (1.4) rotates around a central axis of the safety device and is pushed distally against the biasing force of the spring (1.6) towards the distal position until the guide pin (1.4.1) reaches the distal end of the axial section (1.2.2.2) of the guide track (1.2.2) at the end of the injection stroke, and