Diagnosis in cases with pulmonary lymphangitic carcinomatosis as a primary manifestation is difficult due to unawareness of the cancer. An 81‐year‐old man was admitted due to a one‐week history of dyspnoea and haemoptysis. Chest computed tomography showed diffuse bilateral ground‐grass opacity and partial consolidation. We suspected diffuse alveolar haemorrhage. High‐dose methylprednisolone and cyclophosphamide did not improve his condition and he died from respiratory failure. Autopsy revealed pulmonary lymphangitic carcinomatosis of whole lungs and primary gallbladder cancer. We should consider pulmonary lymphangitic carcinomatosis in the differential diagnosis of patients with haemoptysis and diffuse lung opacity of unknown origin.