Idiopathic osteonecrosis of the medial condyle of the femur, a relatively common disease among Japanese women 60 years or older, is often progressive and requires surgical treatment. In this paper, we report on a case where KAATSU training was effective for a 71-year-old woman with bone necrosis in the left femoral medial condyle revealed by magnetic resonance imaging (MRI). At the first visit, the patient was suffering severe pain, and unable to walk without a cane. After 1 to 2 months of KAATSU training, her pain was mitigated and in about 3 months she was able to walk without a cane. In 6 months she could go upstairs and downstairs using the handrails and about 2 to 3 months later, she no longer needed to use the handrails. MRI revealed marked shrinkage (to 10 mm x 15 mm) of the necrotized region as a result of bone tissue remodeling. From these results, KAATSU training seems to be useful as a new method of rehabilitation for patients with idiopathic osteonecrosis of the medial condyle of the femur.