This paper presents the first report on an endoscopic robot with two manipulators which performed surgical work to resect the mucosal layer of the stomach of pigs without penetrating the body surface. We designed and developed an endoscopic surgical robot system which possesses two arm shaped manipulators for various kinds of surgery in the gastric tubes. The distal part of the manipulator functions as forceps and they are able to hold and handle soft tissues through the cooperative efforts of the right and left arms. And it is also able to incise the gastric wall by holding an electronic scalpel (brought in from the instrument channel) with the manipulator on the right side while opening the sectioning plane on the left side which was take out. With this system we succeeded in the mucosal resection of a large portion of the stomach wall of a pig during experimental surgery. It can be said that this is a new approach robotic surgery in the gastric tube with this kind of surgical robot.