Patent ID: 6921362

Claim:
An outer sheathed endoscope comprising: a flexible insertion portion having a guide channel formed therethrough; a detachable outer sheath covering the flexible insertion portion; a channel tube, a tip end of the channel tube being fixed to a tip end of the outer sheath and passing through the outer sheath, wherein when the outer sheath covers the flexible insertion portion, the channel tube extends through the guide channel; a locking mechanism for restricting the flexible insertion portion from detaching from the outer sheath; and a channel deformation space that permits a part in the vicinity of a tip end part of the channel tube to be elastically deformed when a tip end part of the outer sheath is rotated about an axis in a predetermined range in a circumferential direction with respect to the tip end part of the flexible insertion portion, wherein the locking mechanism is disengaged by rotating the tip end part of the outer sheath about the axis in the predetermined range with respect to the tip end part of the flexible insertion portions, wherein the locking mechanism includes a hook portion and a groove portion, the groove portion being engageable with the hook portion in the circumferential direction, and wherein the hook portion is disengaged from the groove portion when the tip end part of the outer sheath is rotated with respect to the tip end cart of the flexible insertion portion.