A 69-year-old man become aware of myiodesopsia. He visited the Department of Ophthalmology at Keio University Hospital and choroidal metastasis of the right eye was diagnosed. A tumor shadow was detected in the lower lobe of the left lung on chest radiographs, and the serum CEA concentration was found to be significantly increased. Through bronchoscopic examinations, he was confirmed to have primary lung cancer (histological classification: adenocarcinoma). Although detailed systemic examinations were performed, no metastasis to lymph nodes or distant organs except the choroid plexus was detected, which is very rare in a case of stage IV primary lung cancer. In conclusion, it is suggested to be very important to look for ophthalmological abnormalities, even in the case of apparently early lung cancer that seems to be resectable.