The maximum external diameter of a rigid endoscope is restricted for insertion into the human body through small incision, and it is relatively difficult to realize multifunctional endoscopic tool with small diameter. Endoscope that has a transformable mechanism has been developed. When the endoscope is inserted or extracted through the small incision, the shape of the endoscope is straight. In the cavity of the human body, several functions can be realized by transformation, for example, inspection and treatment. In this study, bending joint and folding joint structure are designed and evaluated for transformation.