Patients who undergo organ transplantation are now known to be at increased risk of the development of de novo malignant tumors. This is primarily a consequence of immunosuppression, which may promote tumor development and progression by a variety of mechanisms. It was also reported recently that the relative ratio of lung tumors developing in orthotopic liver transplantation patients was 3.7 times greater than in the general population. We report a case of de novo lung cancer diagnosed in a 65-year-old man 32 months after he underwent liver transplantation for hepatocellular carcinoma secondary to hepatitis C virus cirrhosis. He had received tacrolimus as immunosuppressive therapy after the liver transplantation. The tumor was resected, and he remains well almost 3 years later. Previous reports provide evidence that immunosuppressive therapy is a risk factor for de novo lung cancer; thus, it is important to reduce immunosuppression for orthotropic liver transplantation patients, and to screen them carefully to detect the tumor at an early stage.