A 68-year-old woman slipped while riding a motorcycle and hit her shoulder. She was brought to hospital by ambulance. We diagnosed her as having posterior dislocation of the shoulder joint and greater tuberosity fracture of the humeus. Closed reduction was impossible, so we performed surgery seven days after injury. We made longitudinal skin incision and approached posteriorly. The posterior capsule was detached from the humeral side. There was humeral avulsion of glenohumeral ligament (HAGL). Though we performed osteosynthesis on the greater tuberosity, posterior instability remained. HAGL lesion was repaired by anchor technique, then the humeral head was stabilized. She put on a brace to maintain external rotation for three weeks after surgery. Postoperative JOA score was 100 points.There have been some reports of posterior dislocation of the shoulder joint with humeral head fracture, which is called reverse Hill-Sachs lesion, but few reports with greater tuberisity fracture. In addition, there have been few reports of posterior HAGL, which is called reverse HAGL in fresh posterior dislocation. It is necessary to be careful for posterior HAGL lesion in treatment for posterior dislocations.