A 63-year-old man, who received clopidogrel because of suspected cerebral infarction, visited our hospital as a result of dyspnea on exertion and bilateral infiltration on chest radiograph five months after initiation of clopidogrel. He was admitted to our hospital for further examination of the residual chest abnormal shadow after withdrawal of clopidogrel. Although a lymphocyte stimulation test using whole blood was negative, an increase in the number of lymphocytes and positive lymphocyte stimulation test for clopidogrel were shown in bronchoalveolar lavage fluid. We diagnosed drug-induced pneumonitis caused by clopidogrel based on the laboratory findings and clinical course. After treatment with oral prednisolone, chest radiograph and CT findings dramatically improved. To the best of our knowledge, this is the third case report describing drug-induced pneumonitis caused by clopidogrel.