An adjustment device (1) is provided for adjusting the wear of brake pads and a brake disk of a disc brake, in particular of a pneumatically actuated disc brake. The disc brake includes a brake application device actuated by a rotary lever, which brake application device has an adjusting spindle into which the adjustment device is insertable. The adjustment device is attached to a brake caliper of the disc brake by way of a bearing disk. The adjustment device is provided with a spindle and at least one friction pairing, each friction pairing having two contact surfaces. The friction pairing has a curved cross-section of at least one of its two contact surfaces (17).