A 57-year-old woman was admitted to our hospital for examination of an abnormal shadow in the left middle lung field. The lesion was in S4 of the left upper lobe, with dilation of A5 b and V5 b, and was suspected to be a pulmonary arteriovenous fistula. A three dimensional CT scan showed a tortuous and irregularly dilated vessel. Color doppler imaging showed a mosaic pattern of blood flow. These findings indicated that the fistula was attached to the pleura. The patient underwent thoracoscopic partial resection of the lung.