Total hip arthroplasty (THA) is performed to replace the biological hip joint with an artificial joint for patients who have rheumatoid arthritis or osteoarthritis of the hip joint. Although THA might result in postoperative complications of dislocation, wear and/or loose, their mechanisms have not been analyzed. The hip joint simulator which can generate the desired hip joint angle and the contact force has been developed in order to evaluate the performance of the artificial hip joint. However the effect of muscle forces around a hip joint was not considered in the simulation. In this paper, the effect of the mounting angle of artificial hip joint dislocation is studied using a hip joint simulator considering muscles around a hip joint.