A 70-year-old man with chief complaints of a high fever and bloody sputum was admitted for an intensive examination of pleural effusion of both lungs and pulmonary mass shadows. He was a heavy smoker whose Brinkman Index (BI) was 1,500, and he had a history of occupational exposure to asbestos dust. The direct cause of his death was assumed to be the exacerbation of constrictive pericarditis. An autopsy showed synchronous double cancer, including primary malignant pericardial mesothelioma and primary pulmonary adenocarcinoma and also showed the direct infiltration of malignant pericardial mesothelioma to the left lung and the metastasis of it to the left adrenal gland, the right lung, esophagus, and mediastinal lymph nodes. The autopsy also revealed the existence of the tissue of pulmonary adenocarcinoma, which was obviously different from that of the mesothelioma in the right pulmonary metastatic lesion of the mesothelioma. Moreover, this type of mesothelioma proved to be epithelioid, one that immunohistochemically tested carcinoembryonic antigen (CEA) partially and slightly positive.