Contrary to ventricular mural thrombi, left atrial appendage thrombi are extremely rare in cerebral infarction correlated with acute myocardial infarction but they can be easily detected by transesophageal echocardiography(TEE). We expierienced a case of cerebral infarction which was suspected to be caused from the thrombi in left atrial appendage in a patient with acute myocardial infarction. The cerebral infarction was developed 2 days after myocardial infarction had been occurred and any source of the thrombi could not be detected except in left atrial appendage. The diagnosis was established by TEE and also aided by transthoracic echocardiography, brain computed tomography.