Postoperative junctional ectopic tachycardia (JET) is a narrow complex tachycardia and most frequently occurs during and after surgical repair of certain types of congenital heart defects. Postoperative junctional ectopic tachycardia may produce unfavorable hemodynamics that prolongs stays in the cardiac intensive care unit and hospital, prolongs time on a ventilator, and occasionally requires the use of extracorporeal membrane oxygenation (ECMO) as rescue therapy. The present report describes a rare case of late-onset postoperative junctional ectopic tachycardia, which occurred 13 days after the deployment of a perimembranous ventricular septal defect (PmVSD) occluder in a 17-year-old female teenager. To the best of our knowledge, late-onset postoperative junctional ectopic tachycardia has not previously been reported as a complication in nonsurgical procedures. In this case, the junctional ectopic tachycardia remained resistant to medicines and the haemodynamic imbalance caused a serious life-threatening situation in the patient. The occluder was removed by an emergent thoracotomy; then, the patient was successfully cured by being supported with extracorporeal membrane oxygenation. The findings suggest that during follow-up management, the physician should pay attention postoperatively to junctional ectopic tachycardia even after discharge from the hospital.