We report a case of left ventricular outflow tract (LVOT) obstruction caused by systolic anterior motion of the mitral valve (SAM) following mitral valve plasity (MVP). A 65-year-old man underwent mitral valve plasty for grade III mitral valve regurgitation. The plasty was done smoothly and the patient was weaned from cardiopulmonary bypass successfully with continuous dobutamine infusion. However, about 30 minutes after the weaning, severe cardiovascular collapse developed. Inotropic agent, such as dobutamine, ephedrine, or calcium hydrochloride was not effective. Trans-esophageal echocardiography (TEE) showed severe mitral valve regurgitation with LVOT obstruction due to SAM. The collapse was successfully treated with volume loading and a small amount of a beta1-adrenergic antagonist, landiolol hydrochloride. We conclude that acute LVOT obstruction with SAM could develop following MVP. TEE was a much useful tool for early diagnosis and landiolol hydrochloride would be a notable agent for nonsurgical treatment of LVOT obstruction with SAM.