In recent years, case reports of the pulmonary thromboembolism which had been comparatively less in our country, have been gradually increasing. However, this disease is more often reported in the chronic stage, and case reports of severe cases in the acute stage are still less. The case reported here was admitted to our hospital by emergency ambulation with severe chest pain. On the second day after the admission, respiratory standstill developed suddenly following recurrent chest pain, which necessitated cardiopulmonary resuscitation. The patient was intubated and the IABP was instituted because of hemodynamic instability. An emergent cardiac catheterization under the mechanical ventilation and the IABP supported displayed massive shadow defect on the pulmonary arteriogram, which was indicating acute pulmonary embolism. The pulmonary pressure was 58/18 mmHg despite of the shock state (the aortic pressure: 60/28 mmHg). Subsequently, a pulmonary thrombectomy was carried out under the emergency cardiopulmonary bypass. The cardiac catheterization performed two weeks after the operation. Revealed that the pulmonary pressure returned to the almost normal volume (38/18 mmHg) in association with the aortic pressure of 113/72 mmHg. The venogram of lower extremities revealed thrombi in the deep veins, suggesting the cause of the thromboembolism in the pulmonary arteries. The Bird's nest filter was inserted for the prevention of recurrence of pulmonary embolism. This patient is doing well 10 months postoperatively.