A belt tensioning device for a continuous belt drive. The device includes a torsion spring assembly (20) with a longitudinal axis (A2) and with at least one torsion bar or torsion tube (32). The torsion spring assembly (20) can be clamped axially and in a rotationally fixed way into a rack. A tensioning arm (19), at one end, is arranged at the torsion spring assembly (20) so as to be aligned approximately radially relative to the longitudinal axis (A2). A tensioning roller (15) is rotatably fixed at the other end of the tensioning arm (19). The axis of rotation (A1) of the tensioning roller (15) extends substantially parallel relative to the longitudinal axis (A2) of the torsion spring assembly (20), and the tensioning arm (19) can be resiliently supported relative to the rack so as to oscillate around the longitudinal axis (A2).