An expansible elastic tube (1) in which gas is encapsulated, a medical instrument (an endoscopic camera 2) secured to the tip of the elastic tube (1), a non-expansive tube (3) that is connected to the other end of the elastic tube (1) in such a way as to communicate therewith, the non-expansive tube (3) in which gas is encapsulated, an inextensible body (4) having flexibility, the inextensible body (4) fixed to the elastic tube (1) in a longitudinal direction, a connecting tube (5) having the shape of a hollow circular cylinder and having flexibility and a non-expansive property, the connecting tube (5) connected to the non-expansive tube (3), and a control device (20) which performs variable control of the air pressure inside the elastic tube (1) are provided, and the air pressure is controlled by the control device (20), whereby the elastic tube (1) is made to expand and contract on the side opposite to the inextensible body (4) and the elastic tube (1) is curved at an arbitrary angle.
