This paper presents an advanced locomotion method that produces non-slipping motion in digestive organs and the abdominal cavity. New movement principle of the robot, which has a soft and deformable body that can move through a confined space is proposed. The mechanism of a toy water snake is applied to this principle. Magnetic particles inside the water balloon are affected by the external magnetic field and push the inner side of a balloon to the direction of a magnetic field. We construct an experimental model to verify the proposed principle, the sliding movement is measured using the model. Confirmatory experiments of movement are conducted in the two sheets that imitated internal organs.