A Schwannoma is a benign tumor that originates from Schwann cells in the gastric wall. The tumor is mainly asymptomatic but sometimes can cause bleeding of the upper GI tract. We encountered a Schwannoma that was identified by gastroscopy as a submucosal mass that might be malignant. Therefore, surgery was considered as the primary treatment. The Schwannoma was confirmed retrospectively by a pathologic examination after excising the mass. This case report is a comparative study into Schwanoma with and without central ulceration. Pathologically, atypia of the cell was discovered in the case accompanied by an ulcer, which is a secondary phenomenon caused by the degeneration that does not indicate the malignancy. (Korean J Gastrointest Endosc 2007; 35:243-249)