Interpostion arthroplasty with allograft has been known as a useful option for the shoulder arthropathy, but it has a limitation to immune response. We performed the pectoralis major muscle transfer for shoulder arthropathy. From January 2007 to December 2007, we performed the pectoralis major muscle transfer in 2 patients. They were 1 man and 1 woman, and the mean age of the patients was 70 years (range, 65 to 75). The average follow-up after surgery was 13 months (range, 12 to 14). We analyzed the clinical results by the American Shoulder and Elbow Surgeons (ASES) Score, and evaluated the pain by Visual Analogue Scale. The level of pain reduced from a preoperative average of 10 to a postoperative average of 1. The ASES scores increased from a preoperative mean of 9 to a postoperative mean of 58. These results indicated that interposition arthroplasty with the pectoralis major muscle transfer is a reliable treatment method for the shoulder arthropathy improving shoulder pain, and patient satisfaction.