A 66-year-old woman visited our hospital because of general fatigue. A giant epigastral tumor was pointed out. The abdominal computed tomography revealed a tumor with a size of 15×12×6 cm had irregular internal shadows. A diagnosis of leiomyosarcoma was made by needle biopsy using the abdominal ultrasonography. An operation was performed under the preoperative diagnosis of leiomyosarcoma of the liver. The tumor was located between the liver and stomach and was distinguished from them clearly. The surface of the tumor was irregular and cystic. Intraabdominal leiomyosarcomas are uncommon, especially those arising in the lesser omentum. Fourteen cases of the leiomyosarcoma reported in Japan including this case are reviewed here and possible anatomical geneses are discussed.