Reduced operation for gastric cancer (R1 operation) is indicated for early gastric cancer without lymph node metastasis. We examined which cases can be regarded as early gastric cancer. Mucosal cancer of macroscopically I, IIa, and IIb type that is 2 cm or less in diameter and located at C and macroscopically IIa type submucosal cancer 1 cm or less in diameter appeared to be indicated for this operation. However, preoperative selection of these cases is difficult, and at present, reduction surgery cannot be performed with confidence. Therefore, we have proposed rational surgery for early gastric cancer consisting of removal of the tumor and dissection of group 1 lymph nodes, the lymph node along the left gastric artery, that along the common hepatic artery, and that around the celiac artery. This procedure seems to be appropriate in terms of antitumor immune response of regional lymph nodes and surgical results.