CT scanning of a 77-year-old woman showed a ground-glass opacity pattern shadow (9× 7 mm) in the lower lobe of the right lung. To allow identification of the location of the lesion during thoracoscopic surgery, preoperative barium marking was performed using an ultrathin bronchoscope and virtual bronchoscopic navigation. Virtual bronchoscopy was performed based on thin-section CT images, and virtual bronchoscopic images to the target sites were obtained. Subsequently, using virtual bronchoscopic images to the right B⁸aiiβ x, B⁶biiβ for navigation, an ultrathin bronchoscope was advanced to this site under direct observation. A special catheter for ultrathin bronchoscopy was advanced to sites near the lesion, and barium was infused. The barium was clearly observed by fluoroscopy during thoracoscopic surgery and was useful for determining the resection area. Pathological examination of a resected specimen revealed atypical adenomatous hyperplasia. There were no complications with this method, and a number of target areas could be readily marked in a short time. This method may be useful before thoracoscopic surgery for small peripheral pulmonary lesions.