Appropriate tissue tension and clear visibility of the dissection area using traction are essential for effective and safe endoscopic submucosal dissection (ESD). We developed a robotic assistive traction device for flexible endoscopy and compared its safety and efficiency in ESD between experienced and novice endoscopists. Robotic ESD was performed by experienced and novice endoscopist groups (n = 3, each). The outcomes included time to complete each ESD step, total procedure time, size of the dissected mucosa, rate of en bloc resection, and major adverse events. Furthermore, the incision and dissection speeds were compared between the groups. Twenty gastric lesions were resected from ten live pigs. In the experienced group, the mean incision speed was faster significantly. There was no significant difference in the submucosal dissection speed between the groups. No complications were reported in either group. In conclusion, ROSE can provide simple, effective, and safe multidirectional traction and countertraction during ESD. While performing robotic ESD, experienced endoscopists expressed satisfaction, and novices could perform ESD safely and efficiently. We expect our device to help trainees perform ESD in places where ESD education is difficult to obtain. The device must be made smaller, and its safety and efficacy in humans should be assessed in future studies.