An insertion device includes a long and thin insertion section, a rotating housing that is provided to be rotatable about a longitudinal axis, a drive shaft that is connected to a motor rotating the rotating housing, and that transmits a rotation of the motor, a rotor that is provided at a distal-end side of the drive shaft and that is provided to be movable in relation to the rotating housing in axial direction of the insertion section, and that transmits the rotation to the rotating housing via a coating of the insertion section, a sensor that detects that the rotor moves a predetermined amount in either forward or backward direction relative to the axial direction of the insertion section, and a control unit that controls, according to the detection by the sensor, a state of the motor including a positive rotation, a negative rotation, and rotation halt.
