A 68-year-old woman was admitted to our hospital due to sudden onset of dyspnea. On admission, electrocardiogram (ECG) showed T-wave inversion and QRS prolongation (120 msec) that were not found in her previous ECG. Chest X-ray showed pulmonary edema and cardiac enlargement. Left ventriculogram showed akinesis of the left ventricle except in the basal region. No significant coronary stenosis was found on angiogram. She was diagnosed as having tako-tsubo cardiomyopathy complicated by QRS prolongation. Intraaortic balloon pumping (IABP) was subsequently initiated for the treatment of acute heart failure. QRS prolongation was resolved immediately after the initiation of IABP, and left ventricular dysfunction was resolved within 9 days. She was discharged 14 days later.