A 74-year-old woman was admitted to the hospital of Ehime University School of Medicine because of slight fever, dry cough and dyspnea on exertion. Chest X-ray films on admission showed diffuse infiltrations in both lungs. Drug-induced pneumonia due to the herbal medicine Gosha-jinki-gan was suspected, as Gosha-jinki-gan had been administered for 5 months for the treatment of a right knee pain. Her symptoms and the X-ray abnormality improved after cessation of administration. The lymphocyte stimulation test against Gosha-jinki-gan was positive. To the best of our knowledge, this is the first case of interstitial pneumonia caused by Gosha-jinki-gan.