We report a rare case of a 27-year-old woman with Takayasu arteritis (TAK) complicated by diffuse sclerosing osteomyelitis. She first presented with sclerosing osteomyelitis of the right mandible without evidence of arteritis in the carotid arteries. Eight months later, she complained of left neck pain, and imaging studies revealed the presence of arteritis in the left carotid artery. She was diagnosed with TAK, and immunosuppressive treatment was initiated, which was effective for both the arteritis and the osteomyelitis. Osteomyelitis is an important complication of TAK and bone scintigraphy is useful for its detection.