To enable to improve loose of the sacroiliac joint and to reduce pain caused by the difficulty to open the joint by fixing the pelvis giving a force from the bottom of both wings of the ilium toward the bottom of the sacroiliac joint, which a conventional waist fixing band could not achieve.

Inserting hole 2 is provided at approximately central left side of the band end for the left back part 3, into which the right band end 6 can be inserted. The right band end 6 inserted into the inserting hole 2 is detachable and can be fixed at an appropriate position at the middle band 4 fitting to the body shape as shown in Fig.2 (and not shown here). The left band end 1 also can be fixed at a certain position on the middle band twisting around the body in the opposite direction of the right band end 6. By pulling the left band end 1 and right band end 6, the band can tighten and fix the pelvis from the pubic symphysis 13 toward inferior Sacroiliac joint 7 on either side.