A 60-year-old male with type C chronic hepatitis was admitted to Kibikogen Rehabilitation Center with high fever, cough and general fatigue. Chest X-ray film on admission showed consolidation in the left middle and lower lung lung field. Initial treatment with intravenous ceftazidime, imipenem/cilastatin and clindamycin were ineffective due to continuous high fever and cough and spread of the pneumonia shadow. Administration of minocycline was started for suspected non-bacterial pneumonia whereupon his symptoms improved and the pneumonia shadow began to decrease in size. However, his symptoms and pneumonia shadow worsened after taking him off of minocycline due to progressive pancytopenia and liver dysfunction. He was transferred to our hospital and intravenous erythromycin treatment was initiated for suspected Legionell pneumonia because of the elevation of Legionella micdadei serum antibody titer. Immediately after starting treatment, his symptoms improved and the pneumonia shadow decreased in size. Erythromycin was stopped after the 14th day of administration. In this case, diagnosis of L. micdadei pneumonia was made because of the positive results of the polymerase chain reaction test and elevation of the L. micdadei serum antibody titer (from 0 to 1,024). This is the second report of a L. micdadei pneumonia case here in Japan.