Recently, laparoscopic surgery has become increasingly popular because of its lesser invasiveness, including smaller incisions, and fewer post-operative complications. It is also possible to observe the abdominal cavity by laparoscopy. We report a hepatocellular carcinoma arising in an accessory liver lobe detected during gynecological laparoscopic surgery. A 48-year-old woman who was undergoing laparoscopic hysterectomy for uterine fibroids was found to have a protruding, extrahepatic pedunculated tumor by intraoperative observation of the abdominal cavity during the fibroid procedure. We suspected FNH based on preoperative imaging findings, including abdominal ultrasound, computed tomographic scanning, and magnetic resonance imaging. We performed a laparoscopic partial hepatectomy. The cut surface of the tumor was similar to normal liver tissue. The pathological findings identified normal liver tissue and vessels, suggesting it was the accessory liver lobe. It also included a well-differentiated hepatocellular carcinoma. The final diagnosis was hepatocellular carcinoma arising in the accessory liver lobe. There have been no prior reports of extrahepatic liver tissue detected during gynecological surgery. This case reminded us of the importance of intra-abdominal observation during laparoscopic procedures. The opportunities to discover other cases of extrahepatic liver tissue by laparoscopy will increase.