A 60-year-old man was admitted to our hospital complaining of general malaise for a few months, discomfort of the right shoulder and fever in May 2003. Chest X-ray film showed an infiltrative shadow in the right lung field and chest CT scan revealed right pleural effusion. Pulmonary tuberculosis complicated with pleurisy was first suspected from the findings of high ADA level of the effusion and positive result of PPD skin test. But, microscopic examination of the specimens obtained by transbronchial lung biopsy disclosed granulomatous lesions and Mycobacterium kansasii was identified from all specimens; sputum, fluids of brushing and bronchial washing. The patient was diagnosed as pulmonary Mycobacterium kansasii infection and treated with anti-tuberculous drugs including RFP. His clinical course was good and no recurrence of pleural effusion was seen. This case was a rare case of pulmonary Mycobacterium kansasii infection complicated with pleural effusion.