Recently, the need of colonoscopy is increasing because of the rise of colonic disorder including cancer of the colon. However, current colonoscopy depends on doctor's skill strongly. Therefore, a large intestine endoscope which does not depend on the techniques of a doctor with high safety is required. In this research, we aim at development a novel large intestine endoscope which can change own stiffness partially and realize safe insertion without specific techniques. In this paper, we have developed a device which changes own stiffness and applying it to a prototype large intestine endoscope. The device consists of fiber-reinforced silicone rubber and is able to change its stiffness by air pressure. The effectiveness of this device was analyzed by nonlinear FEM (finite element method) and was confirmed experimentally. In addition, we developed a prototype of the large intestine endoscope changing its stiffness by linking some stiffness change devices and verified the effectiveness by fundamental insertion experiments in U-shaped route.