Recently, laparoscopic and endoscopic cooperative surgery (LECS) for submucosal gastric tumor has been developed to avoid an excessive surgical resection of gastric wall, which causes a deformity of the stomach and reduced oral intake. We report here a case of failed LECS for gastric submucosal tumor, and discuss the cause of failure. An 89-year-old woman underwent LECS for an intraluminal type submucosal tumor involving the upper and posterior gastric wall. Specifically, two sites of the gastric wall were fixed with subumbilical and left latero-abdominal wall approaches and two trocars with balloons were introduced into the stomach. Endoscopic submucosal resection was performed circumferentially around the tumor. Then, we tried to lift the tumor using an Endo-loop®. However, the amount of lifting was not sufficient for a safe surgical resection because the surgical field was extremely narrow. Therefore, we converted LECS to open surgery. In conclusion, it is important to consider clinical factors such as body size, tumor size and tumor location when planning LECS. Particularly, the intraabdominal suturing technique instead of using a linear stapler is desirable for a tumor involving the posterior wall.