Primary hepatic gastrinoma is very rare, with fewer than 20 cases reported. We describe a 44-year-old woman in whom primary hepatic gastrinoma was strongly suspected clinically. The patient was referred to our hospital because of intractable diarrhea. She had elevated serum levels of alanine aminotransferase, aspartate aminotransferase, and fasting gastrin. A calcium provocative test showed a marked elevated serum gastrin level (17,000 pg/ml). Abdominal ultrasonography, computed tomography, and magnetic resonance imaging revealed a tumor in the right lobe of the liver, measuring 38 x 33 mm. No other tumor was detected in the pancreas, duodenum, or local lymph nodes on preoperative radiological imaging or endoscopic ultrasonography. The hepatic tumor was resected. Total intraoperative ultra-sonography and intraoperative exploratory palpation of the duodenum, pancreas, and lymph nodes showed no evidence of an extrahepatic tumor. Pathological findings and immunohistochemical studies revealed a neuroendocrine tumor with increased production of gastrin. Postoperatively, the serum gastrin level returned to normal.