We report a rare case of pancreaticobronchial fistula caused by chronic pancreatitis. A 46-year-old man with a history of chronic alcoholic pancreatitis was referred to us for investigation of dyspnea and bloody sputum. Chest radiography showed a bilateral pneumonia-like shadow, with severe atelectasis in the left lower lung field. Abdominal computed tomography showed a huge pancreatic pseudocyst in the left upper abdomen. The pseudocyst extended as a soft mass from the retroperitoneum into the posterior mediastinum with gas. The pancreatic amylase level in the sputum was 57,500 IU/l. The organism cultured from the sputum was Pseudomonas aeruginosa. Based on these findings, we diagnosed a pancreaticobronchial fistula created by the infected pseudocyst penetrating directly through the dome of the diaphragm to the bronchial tree. External drainage of the infected pseudocyst improved the patient's respiratory condition, allowing him to undergo distal pancreatectomy and splenectomy. Thereafter, he did not suffer any further symptoms.