Abstract: A belt tensioning device comprises a base member having an attachment portion and an opening for a drive shaft; first and second tensioning arms that are pivotably supported by first and second bearings on the base member around first and second pivot axes and have first and second tensioning rollers 5, 7. A spring arrangement pretensions the two tensioning arms in a circumferential direction towards each other; wherein the spring arrangement has at least one bow-shaped spring that has a circumferential extension of less than 360° around the first and the second pivot axis; wherein the at least one bow-shaped spring has first and second support portions that are supported on the first and second tensioning arm as well as a spring portion extending between the first and second support portion; wherein the at least one bow-shaped spring has an axial length in the area of the first and the second support portion which is axially shorter than a total axial length of the bow-shaped spring.