The invention relates to a method for machining the interior of a brake caliper (1) of a disc brake, on which are formed: —a first saddle portion to the one side of the brake disc of the disc brake, —a second saddle portion to the other side of the brake disc, and —a bridge section connecting the saddle portions and providing a free space for at least a part of the brake disc. At least one of the saddle portions is provided with a hollow space (7) for receiving a brake application device, wherein said hollow space comprises a mounting opening (4) towards the free space and extends in the opposite direction until a saddle rear wall (18). At least one support surface for the forces acting during the brake application is formed on the inner side of the saddle rear wall. The machining of the support surface (20) is carried out from the direction of the free space and, for this purpose, a tool (55) is brought from outside of the brake caliper (1) into the hollow space. In order to provide a method for machining the interior of a brake caliper of a disc brake, which allows a high-precision machining of the support surfaces inside the brake caliper even in the case of the narrow space conditions which are typical for the machining of a single-piece brake caliper, the tool (55) is guided into the cavity through another opening (25) than the mounting opening (4).