A 54-year-old woman, complaining of a dry cough in the beginning of December 2004, was admitted to our hospital because of its exacerbation in January 2005. Interstitial pneumonia was suspected according to a chest Xray and chest CT. The pathological diagnosis of cellular nonspecific interstitial pneumonia (NSIP) was made after video assisted thoracic surgery. She did not have muscle weakness or arthralgia but she had a skin lesion ("mechanic's hand") which is often seen in patients with antisynthetase syndrome. Anti-Jo-1 antibody was negative but anti-OJ antibody was positive. Therefore, anti-aminoacyl tRNA synthetase syndrome with cellular NSIP was diagnosed. She had a favorable response to the initial treatment of methylprednisolone pulse therapy followed by prednisolone 1 mg/kg/day. Her symptoms, pulmonary function test and chest imaging findings have showed improvement after therapy.