Provided are a surgical apparatus for an endoscope and an exterior tube that can supply a pneumoperitoneum gas into a body cavity without causing degradation of operability. An exterior tube is sheathed to an outer tube insertion part of an outer tube that is inserted into a body cavity through a body wall and guides an endoscope and a treatment tool into the body cavity, and an outer peripheral surface of the exterior tube is provided with a locking part that restricts the forward and backward movement of the exterior tube with respect to the body wall and the rotation of the exterior tube around an axis. A gap between an inner peripheral surface of the exterior tube and an outer peripheral surface of the outer tube insertion part is used as an air supply passage for supplying the pneumoperitoneum gas within the body cavity.
