Pulmonary thromboembolism (PTE) is a serious postoperative complication. Prompt diagnosis of PTE is important but it is difficult because clinical manifestations of PTE are not obvious in most cases. A 59 year-old woman received cholecystectomy and choledocholithotomy under general anesthesia. At the 9th postoperative day, syncope, hypoxemia and hypotension were developed suddenly and the patient was transfered to intensive care unit. PTE was suspected with hemodynamic monitoring from pulmonary arterial catheter and echocardiography and diagnosed with lung perfusion scan and venogram of lower extremities. Proper cardiopulmonary support was done and the patient was recovered and discharged in improved condition. In conclusion, if a patient have syncopal attack with shock in postoperative period, PTE must be thought to be an one of possible causes of syncope and thoroughly investigated.