An overtube device includes: a tube body having a bending part and a main body part； a wire having a distal end part fixed to the bending part and a proximal end part positioned on the proximal end side and extending along a longitudinal axis； an operation part capable of pulling the wire to the proximal end side； and an overtube base having a stopper that fixes the tube body in a longitudinal axis direction so as not to advance and retract, and engages with the operation part in a state where the wire is pulled toward the proximal end side of the wire so as to hold a curved shape of the bending part. When a medical device inserted into the tube body is retracted, an engagement between the operation part and the stopper is released, and holding of the curved shape of the bending part is released.
