Medical treatment endoscope

A medical treatment endoscope comprising:

• a sheath having a flexibility;
• arm members configured to be capable of advancing from and retracting into the sheath, and having a bending part that projects out from a front end of the sheath and performs bending actions;
• a wire member configured to bend the bending part;
• an open/close mechanism which directs the arm members from a direction along a central axis of the sheath to a rotational direction deviated from the central axis of the sheath around a base axis of the arm members, and from the rotational direction deviated from the central axis of the sheath around the base axis of the arm members to a direction along the central axis of the sheath;
• a viewing device and an illuminating member that are disposed to a front end side of the sheath;
• the open/close mechanism includes:
• an open/close operating member, configured to open the arm members by moving in a proximal end direction of the sheath, the open/close operating member at least partially protrudes from an opening of a distal end of the sheath and inserted in a freely advancing and retracting manner into the sheath;
• linking parts, connected to the open/close operating member at a first end thereof and connected to a proximal position of the arm members at a second end thereof, and configured to be capable of turning according to the open/close operating member which advances and retracts for converting an advance/retract action of the arm members into an open/close action around the base axis of the arm members of the open/close mechanism;
• and
• supporting members connected to the linking parts at a first end of the supporting members to be rotatable and connected to the sheath to freely advance and retract so as to support the arm members;
• wherein the arm members comprise two arm members that are arranged in a radial direction of the sheath, and at least one part of the open/close operating member is disposed at a position in an area between central axes of the two arm members in a cross-section along the central axis of the sheath.