Pulmonary arteriovenous malformation (PAVM) is an uncommon congenital anomaly. As PAVM is a direct communication between branches of the pulmonary artery and vein, severe hypoxemia, paradoxical embolism, and massive hemorrhage can result. We present a 39-year-old woman with severe hypoxemia after the induction of one lung ventilation (OLV) for resection of a PAVM in her right lower lobe. We analyzed the cause of hypoxemia by an arterial blood gas analysis and estimated shunt equation. The preoperative value of an intrapulmonary shunt (Qs/Qt) was 15%. However, after the OLV, the values of Qs/Qt increased to 48% with 92.1% arterial oxygen saturation (SaO2). After the resection of PAVM, the value of Qs/Qt decreased to 36% during the OLV, and postoperative value of Qs/Qt and SaO2 were in the normal range. These findings represent that PAVM patients are prone to severe hypoxemia and an abnormally high Qs/Qt, which might be induced by the increase of pulmonary vascular resistance during OLV.