To provide a retainer for spread legs which enables the regulation of a spreading degree at which legs are spread without an unnecessary load to be brought to bear upon the legs and therefore, ideally serves the purpose of therapy for a hip joint, when medically treating the hip joint.

This retainer consists of a main framework 1 with a formed space into which one of the legs of a patient can be introduced and an auxiliary framework 2 on which the other spread leg can be placed. In addition, the auxiliary framework 2 is fixed to the main framework 1 at a changeable angle and position, so that the degree of inclination of the auxiliary framework 2 with the main framework 1 can be regulated. Further, fastener bands 10, 16 for immobilizing the legs in the main framework, 1 and on the auxiliary framework 2 are arranged. Besides, an anchoring means for maintaining the auxiliary framework 2 whose angle and position are changed, in an optimal state of inclination, e.g. a supporting arm 18, is provide. Thus, it is possible to continuously keep the legs spread at the best angle and position for the therapy of a hip joint.