An autopsy case of primary systemic amyloidosis with severe cardiac amyloidosis in a 75-year-old Japanese man is reported. The initial signs were dyspnea and cough, followed by general fatigue and loss of appetite. Heart failure, pleural effusion, and liver cysts were found on physiological examination. Autopsy findings were primary systemic amyloidosis with severe diffuse cardiac amyloidosis and cardiac hypertrophy (585 g). Focal necrosis by infarction was found in the liver and spleen. The cause of amyloidosis was unknown.