The invention relates to a torsion adjuster, comprising a main shaft unit, an immobilization unit, an elastic pushing unit and an adjusting unit. The main shaft unit consists of a first tool head piece with an immobilizing ring gear and a second tool head piece. The immobilization unit comprises a bearing base which is arranged at the first tool head piece and is close to the immobilizing ring gear, a plurality of immobilizing pieces and an ejector block. The bearing base has a plurality of accommodation tanks used for accommodating the immobilizing pieces. The immobilizing pieces are limited among the accommodation tanks and the ejector block and the immobilizing ring gear. The elastic pushing unit can apply an axial thrust on the ejector block so as to move the immobilizing pieces towards the immobilizing ring gear constantly, so that a rotating immobilizing force is generated and applied on the first tool head piece. The adjusting unit is installed on the second tool head piece and can adjust the axial thrust of the elastic pushing unit. Thus the invention can improve the adjusting accuracy and enhance the intensity of the overall structure so as to raise the working efficiency.