1. A protective device (1) for a pre-filled syringe (2), containing a hollow support body (1.2), an unfastening sleeve (1.4), located without the possibility of rotation in the support body (1.2), with the possibility of moving relative to it, while - a guide (1.2.4) is formed in at least one essentially flat side wall (1.2.1) of the support body (1.2), - the release sleeve (1.4) contains at least one flexible arm (1.4.5) with a guide pin (1.4.6) extending from the flexible lever (1.4.5) and protruding through the guide (1.2.4), - the guide The finger (1.4.6) is movable within the guide (1.2.4) and along it in a plane defined by a substantially flat side wall (1.2.1), characterized in that the hollow support body (1.2) has a detachable mounting means (1.2.6) made with the possibility of pressing a pre-filled syringe (2) to the sleeve (2.2.2) of the cylinder for installing a pre-filled syringe (2) in the supporting body (1.2), while the protective device (1) further comprises: - a hollow outer body (1.3) installed with the possibility of sliding about relative to the supporting body (1.2) and made with the possibility of receiving the supporting body (1.2), while the release sleeve (1.4) is made with the possibility of unlocking the installation means (1.2.6), - the guide rail (1.3.5), formed at least , on one essentially flat inner surface of the outer body (1.3), while the guide rail (1.3.5) is made with the possibility of abutment against the guide pin (1.4.6) to guide the movement of the guide pin (1.4.6) along the guide (1.2 .4) when the outer body (1.3) slides relative to the support1. Защитное устройство (1) для предварительно заполненного шприца (2), содержащее- полое опорное тело (1.2),- раскрепляющую втулку (1.4), расположенную без возможности вращения в опорном теле (1.2), с возможностью перемещения относительного него,при этом- по меньшей мере, в одной по существу плоской боковой стенке (1.2.1) опорного тела (1.2) образована направляющая (1.2.4),- раскреп
