The invention proposes a disc brake having a brake caliper (1) and a tensioning device arranged therein for applying force to the brake linings of the disc brake, wherein part of the tensioning device is a brake lever (10) which can be actuated by a force element and preferably by a compressed air cylinder. The brake lever is composed of a lever arm (14), against which the force element is supported, and a brake application shaft (15), which is supported against a pressure piece (8) acting towards the brake linings, and is also supported from the inside against the brake caliper, wherein the brake caliper (1) and the brake application shaft (15) face each other and are formed as shells (21, 22) in which a supporting roller (20) with a roller axis (A) running transverse to the tensioning direction (Z) is mounted. To keep the mutual movability of the parts involved low by the simplest measures possible and without the need for additional parts, the supporting roller (20) is supported with the lateral surface (20A) thereof directly in one of the two shells (21, 22) and is designed to be non-rotatable or have only limited rotational movement with respect to this shell. The supporting roller (20) also serves as a means to centre the brake lever (10) laterally in the brake caliper. A supporting roller particularly suited to these purposes is also to be created.