Since 2010, we have used single-incision laparoscopic surgery (SILS) for patients with a gastric submucosal tumor, as a less invasive alternative to conventional laparoscopy. From September 2010 to January 2011, five patients underwent a local resection for a gastric submucosal tumor using a SILS™ port at Keio University Hospital. We performed partial gastrectomy via the SILS™ port using a 5 mm flexible endoscope, a vessel sealing system, and a stapling device. There were no major intraoperative complications, conversion to laparotomy, or cases of tumor rapture. The average operative time was 89 (range, 72-129) minutes with minimal blood loss. Pathological examination revealed four cases of gastrointestinal stromal tumor and one case of inflammatory fibrosis caused by nonspecific inflammation. Although we examined only a small number of cases in this study, the results suggested that SILS gastrectomy can be performed safely and effectively for gastrointestinal stromal tumor.