We report a case of successful control of the infection of megaprosthesis in the distal femur. Deep infection occurred 5 years after the resection of the osteosarcoma and reconstruction with cernentless megaprosthesis. Multiple debridement and intravenous administration of antibiotics did not eradicate the infection. He developed aortitis syndrome (Takayasu's arteritis) and needed to undergo steroid therapy. Total removal of the prosthesis achieved good control of the infection, and the patient had started prednisolone therapy. The patient can walk alone with an ischial weight-bearing brace. Removal of the endoprosthesis and application of ischial weight-bearing brace may be a possible option for the treatment of infected megaprosthesis.