A belt retractor having a belt shaft having a shaft body, a profile head and a torsion bar, wherein the torsion bar arranged in the shaft body is connected on one end to the shaft body and on a second end to the profile head, and the profile head can be securely attached to the vehicle, and having a belt pretensioner, wherein a pretensioner drive wheel of the belt pretensioner is directly connected in a rotationally fixed manner to the profile head of the belt shaft, and mass bodies can be engaged with the pretensioner drive wheel so as to transmit force to drive the belt shaft in winding direction. The pretensioner drive wheel (16) is configured by means of two parts, the profile head (1) of the belt shaft and a push-on ring (2) that is pushed onto the profile head (1) and is positively and non-positively connected thereto, wherein respectively mutually opposite dome-shaped partial receiving socket segments (3), which form together receiving sockets for the mass bodies, are formed on the profile head (1) and on the push-on ring (2).