A disk brake includes a brake disk, a brake caliper, at least one application device lying within the brake caliper on one side of the brake disk, an axially movable device configured to move a brake pad axially toward the brake disk by way of at least one actuating spindle when the brake is actuated, and an adjustment mechanism configured to rotate the actuating spindle because of a rotational coupling acting in the direction of rotation. The adjustment mechanism comprises a thread device, which, at least in the case of rotation in a second direction of rotation opposite a direction of rotation, is configured to mesh with an external thread of the actuating spindle and is configured to screw the adjustment mechanism in relation to the actuating spindle.