The medical treatment endoscope according to the present invention includes a sheath having a flexibility at least one arm member having a bending part that projects out from a front end of the sheath and performs bending actions an open/close mechanism which directs the arm member from a direction along a central axis of the sheath to a direction deviated from the central axis of the sheath, and from a direction deviated from the central axis of the sheath to a direction along the central axis of the sheath and a viewing device and an illuminating member that are disposed to the front end side of the sheath.
