According to the invention, a safety device for a pre-filled syringe comprises of a needle shield adapted to cover an injection needle of the pre-filled syringe before and after an injection, a support body with at least one pivoting arm adapted to engage a barrel collar of the pre-filled syringe and an outer body with a first inner sleeve comprising a bevelled section. The needle shield, the support body and the outer body are telescopically arranged. The needle shield, the support body and the outer body may telescope with respect to each other to cover and to expose the injection needle of the pre-filled syringe. The bevelled section is arranged to abut against the pivoting arm connected to the support body by a living hinge to deflect the pivoting arm radially inwards, so that the pivoting arm may engage the barrel collar after a dose of a medicament contained in the pre-filled syringe has been disposed beneath the skin of a patient receiving the injection.