Abstract: Flexible devices such as colonoscopy tube or catheter being inserted into the human-body make contact with the human tissues at several locations. Excessive contact force may damage the human tissues. To cope with this problem, the first aim of this paper is the shape estimation of the flexible body inside the human body using only two electromagnetic sensors. For this, the flexible body is modeled as kinematically redundant manipulator with many joints and links. The second aim is to estimate contact forces at a point, line contact, and multiple points. Cosserat-rod theory is employed to solve this problem. The effectiveness of the proposed algorithms is proved through both experiment and simulation for a flexible colonoscopy tube.