Belt tensioner

A belt tensioner 1 comprises a base part 3 having side flanges 2, 2.1, a clamping lever 5 pivotally connected thereto, and a locking device for locking the clamping lever 5 in its closed position. The locking device has a spring element 7 arranged on the inner side of the clamping lever 5 with a bolt 9 projecting from the clamping lever 5 in its closed position in the direction of the adjacent side flange 2, 2.1 of the base part 3, and a bolt catch 10 associated with this side flange 2, 2.1 with a bolt opening 11. The bolt 9 engages in the bolt catch 10 in the closed position of the belt tensioner 1 and is held therein by the spring element 7 to block an opening movement of the clamping lever 5. The spring element 7 has a handle 18 projecting on the inner side of the clamping lever 5 beyond its free end, which lies opposite the articulation of the clamping lever to the base part 3, for adjusting the bolt 9 out of the bolt catch 10 into the bolt opening 11 against the force of the spring element 7.