A fastening device for fastening add-on parts on carrier components has a plug-in locking device, for locking to a carrier component, and a releasable rotary locking device, spaced apart axially from the plug-in locking device and intended for locking to an add-on part. The rotary locking device has an axial supporting element and at least one locking wing, spaced apart axially from the supporting element and extending away radially from a shank of the fastening device. The supporting element and the at least one locking wing have axial locking surfaces, located axially opposite one another. The axial locking surface of the supporting element is arranged axially between the locking wing and the plug-in locking device. The rotary locking device also has a rotary locking stop, which delimits the rotating-in and/or rotating-out action.