The invention relates to an injector for a common rail injection system of an internal combustion engine, having an injector housing, a valve element disposed in the injector housing, a sealing ring acting as a seal between a high-pressure region and a low-pressure region of the injector, and a support ring, disposed together with the sealing ring in an annular chamber between the injector housing and the valve element, for bracing the sealing ring, which is provided, in its underside remote from the sealing ring, with a plurality of relief grooves spaced apart in the circumferential direction and, in its outer circumferential edge, with a plurality of recesses spaced apart in the circumferential direction. The relief grooves and the recesses are disposed in offset fashion in the circumferential direction.