A 65-year-old man with previous history of congestive heart failure and genetically proven Becker muscular dystrophy (BMD) was suddenly suffered from aphasia and right hemiplegia. Physical examination showed severe motor aphasia, right hemiplegia, and signs of left heart failure. An echocardiogram before the onset of aphasia showed markedly dilated left ventricle and decreased ventricular contraction. Intracardiac thrombus was not detected. Although his electrocardiogram on admission showed sinus rhythm, atrial fibrillation was noted at the time of neurological deterioration. MRI of the brain revealed acute infarction in the territory of the left middle cerebral artery and the left anterior inferior cerebellar artery. MR angiography showed vascular occlusion at the left M2 segment. Cerebral embolism due to atrial fibrillation associated with BMD-related DCM was diagnosed. While an administration of anti-coagulant, diuretics, and dopamine relieved his respiratory distress and right hemiplegia, severe motor aphasia persisted. Cerebral embolism may be a notable complication in patients with BMD presenting with late-life expression of skeletal muscular weakness and antecedent cardiac involvement.