A self-locking safety belt retractor has a blocking apparatus for a belt shaft mounted rotatably in a housing. The blocking apparatus includes a pawl inserted into a recess of the shaft front of the belt shaft which can be pivoted radially outward into engagement with the blocking apparatus. A blocking gearing (12) is oriented with respect to stop surfaces of the pawl (16) and to force transmission surfaces (25, 32) of the recess (15) such that, when the gear teeth of the pawl (16) are engaged in the blocking gearing (12) under normal load, a force acts between the blocking gearing (12) and the belt shaft (13) in a radial direction. If the load increases in a crash case, a force is transmitted in the circumferential direction due to plastic deformation of at least one housing gear tooth (28, 26) of the blocking gearing (12).