An end fitting tensioner (10) for a seat belt system includes a rotatable belt shaft (12) to which one end (14) of a webbing (16) is fixed, a belt shaft housing (18) in which the belt shaft (12) is supported, a rope reel (36) which is arranged at an axial end of the belt shaft (12) and is connected to the belt shaft (12) in a rotationally fixed manner, as well as a pull rope (41) which is secured by one rope end (45) on the rope reel (36) and can at least partly be wound onto the rope reel (36). The rope reel (36) includes a winding surface (62) for the pull rope (41) that is conically tapered in the axial direction.