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 configured to fix the tube body in a longitudinal axis direction so as not to advance and retract, and configured so that the operation part is provided in a state where the wire is pulled toward the proximal end side of the wire until a curved shape of the bending part is held. In a state where the operation part is mounted on the overtube base, the overtube base holds the wire in a state where the wire is pulled toward the proximal end side of the wire.
