An endoscope comprising: an insertion unit insertable into a body cavity; an operation unit that comprises a distal end part connected to a proximal end part of the insertion unit, with the insertion unit being allowed to rotate axially about a lengthwise direction of the insertion unit as an axis, and configured to operate the insertion unit; an operation-unit mouthpiece part engaged in the distal end part of the operation unit; an insertion-unit mouthpiece part integrally engaged in the proximal end part of the insertion unit, and connected to and directly inserted into the operation-unit mouthpiece part to be axially rotatable about the axis in a manner that the insertion unit is axially rotatable about the axis connected to the operation unit; a rotary operation unit connected to the insertion-unit mouthpiece part, axially rotatable along with the insertion-unit mouthpiece part and configured to be operated to allow the insertion unit to be axially rotatable about the operation unit via the insertion-unit mouthpiece part; a support member configured to support the rotary operation unit; a pin, wherein the support member is fixed to the insertion-unit mouthpiece part by the pin and the rotary operation unit is connected with the insertion-unit mouthpiece part through the support member and the pin; a water-tight sealing member that ensures water-tightness between the insertion unit and the operation unit; and a torque control member that is provided at a different position from the water-tight sealing member, is provided between the operation-unit mouthpiece part and the insertion-unit mouthpiece part in radial directions of the insertion unit, so as to always make tight contact with the operation-unit mouthpiece part and the insertion-unit mouthpiece part which are connected to each other, and is configured to control resistive torque of the insertion unit during rotation of the insertion unit by applying frictional resistance in directions about the axis to the insertion unit when the insertion unit rotates in relation to the operation unit by the rotary operation unit axially rotatable about the axis along with the insertion-unit mouthpiece part, characterized in that the water-tight sealing member that tightens the proximal end part side of the insertion unit, and the torque control member that tightens the proximal end part side of the insertion unit, are configured so that frictional force accompanying rotation of the torque control member is greater than frictional force accompanying rotation of the water-tight sealing member. an insertion unit insertable into a body cavity; an operation unit that comprises a distal end part connected to a proximal end part of the insertion unit, with the insertion unit being allowed to rotate axially about a lengthwise direction of the insertion unit as an axis, and configured to operate the insertion unit; an operation-unit mouthpiece part engaged in the distal end part of the operation unit; an insertion-unit mouthpiece part integrally engaged in the proximal end part of the insertion unit, and connected to and directly inserted into the operation-unit mouthpiece part to be axially rotatable about the axis in a manner that the insertion unit is axially rotatable about the axis connected to the operation unit; a rotary operation unit connected to the insertion-unit mouthpiece part, axially rotatable along with the insertion-unit mouthpiece part and configured to be operated to allow the insertion unit to be axially rotatable about the operation unit via the insertion-unit mouthpiece part; a support member configured to support the rotary operation unit; a pin, wherein the support member is fixed to the insertion-unit mouthpiece part by the pin and the rotary operation unit is connected with the insertion-unit mouthpiece part through the support member and the pin; a water-tight sealing member that ensures water-tightness between the insertion unit and the operation unit; and a torque control member that is provided at a different position from the water-tight sealing member, is provided between the operation-unit mouthpiece part and the insertion-unit mouthpiece part in radial directions of the insertion unit, so as to always make tight contact with the operation-unit mouthpiece part and the insertion-unit mouthpiece part which are connected to each other, and is configured to control resistive torque of the insertion unit during rotation of the insertion unit by applying frictional resistance in directions about the axis to the insertion unit when the insertion unit rotates in relation to the operation unit by the rotary operation unit axially rotatable about the axis along with the insertion-unit mouthpiece part, characterized in that the water-tight sealing member that tightens the proximal end part side of the insertion unit, and the torque control member that tightens the proximal end part side of the insertion unit, are configured so that frictional force accompanying rotation of the torque control member is greater than frictional force accompanying rotation of the water-tight sealing member.