A 48-year-old man with diabetes mellitus and alcholic chronic pancreatitis was admitted to our hospital with fever and dyspnea. Chest x-ray film showed infiltration of the right upper lung field and blood exam demonstrated marked increase in CPK and renal dysfunction. Intravenous ceftriaxone sodium was started, but the next day, we started intravenous ciprofloxacin because the urine sample was positive for the Legionella antigen. Hemodialysis was started for acute renal failure due to rhabdomyolysis, and mechanical ventilation was introduced due to worsening of acute respiratory failure. Despite these treatments, bilateral infiltration on chest x-ray worsened, resulting in acute respiratory distress syndrome (ARDS). After administration of intravenous pulse methylpredonisolone and sivelestat (neutrophil elastase inhibitor), the patient was successfully weaned from mechanical ventilation. He was also removed from hemodialysis, and discharged from hospital with a good performance status 28 days later. The outcome in this case suggested that treatment with pulse steroid and sivelestat sodium in addition to antibiotics may be effective for Legionella pneumonia complicated by ARDS and acute renal failure.