A strap tightener comprises a support (1) and a reel (2). The support (1) has two opposing side plates (1a). Each of the two side plates (1a) is provided with a reel hole (1b). Each of two ends of the reel (2) is provided with a ratchet portion (2a). The ratchet portions (2a) are located in the corresponding reel holes (1b), and can rotate in the reel holes (1b) along with the reel (2). An upper inner wall of the reel hole (1b) is provided with a recessed engaging portion (1d). Under external force, the ratchet portion (2a) can move eccentrically to enable one of ratchet teeth to engage with the engaging portion (1d). The ratchet portion of the strap tightener of the present invention is disposed in the reel hole, and can move, under tension, eccentrically to engage with the engaging portion after tightening, and the engaging portion is disposed on the support such that the overall strength of the strap tightener is high, and the strap tightener does not deform and fail even after long-term use, and has a desirable tightening effect and stability after tightening. The invention resolves the problem in which a non-return buckle of a prior art cord tightener has poor strength, is prone to deformation and failure after long-term use, and in which a cord thereof may become loose, resulting in a poor tightening effect and poor stability after tightening.Linvention concerne un tendeur de sangle comprenant un support (1) et une bobine (2). Le support (1) possède deux plaques latérales (1a) opposées. Chacune des deux plaques latérales (1a) est pourvue dun trou (1b) de bobine. Chacune des deux extrémités de la bobine (2) est pourvue dune partie rochet (2a). Les parties rochet (2a) sont situées dans les trous (1b) de bobine correspondants, et peuvent tourner dans les trous (1b) de bobine conjointement avec la bobine (2). Une paroi interne supérieure du trou (1b) de bobine est pourvue dune partie (1d) de mise en prise en retrait. Sous leffet dune force externe, la partie roche
