An 85-year-old woman complaining of nausea was admitted to our hospital after being found to have complete atrioventricular block. We diagnosed the patient with infective endocarditis after observing vegetation on transesophageal echocardiography (TEE) and detecting Pseudomonas aeruginosa in a blood culture. The patient had no history of intravenous drug use, instrumentation or valvular disease. Although sensitive antibiotics were administered intravenously, the second TEE performed on the 10th day demonstrated increased vegetation. The patient developed septic shock and died on the 14th day. To our knowledge, this is the first report of infective endocarditis caused by community-acquired Pseudomonas aeruginosa in Japan.