We describe a 35-year-old man with hepatocellular carcinoma (HCC) that recurred in the diaphragm after right hepatic lobectomy. The patient had undergone right hepatic lobectomy for HCC with chronic hepatitis B virus infection 1 year previously. On pathological examination, the tumor measured 15 × 14.4 × 11 cm and was moderately well differentiated. The surgical margins were negative. After 1 year, computed tomography of the abdomen revealed a mass extending from the right side of the diaphragm to the retroperitoneal space. The mass was enhanced in the early phase and washed out in the late phase. Extrahepatic recurrence of HCC in the diaphragm was diagnosed. We performed tumor resection with partial resection of the right side of the diaphragm and wedge resection of the right lower lobe of the lung. The diaphragm was reconstructed with a sheet of artificial pericardium. The histopathological diagnosis was recurrence of HCC in the diaphragm with invasion of the right lung. The postoperative course was uneventful, and the patient was discharged on postoperative day 8. He underwent chemotherapy with cisplatin and 5-fluorouracil. After 9 months, the patient died of unresectable recurrence of HCC in the brain. No recurrence was detected in the right subphrenic area.