A supporting disk for providing bearing support to a rotor of an open-end spinning machine, the supporting disk including a bearing ring and a supporting ring which is made of an elastic polymeric material and mounted on the periphery of the bearing ring. The bearing ring has a side ring on at least one of the sides of its outer edge. The side ring is located at a distance from the outer edge, connected to the bearing ring via holding members, and is also provided with a supporting ring on its periphery.