A lens tube includes a lens guiding frame, a main unit, and a position detecting device. The lens guiding frame holds a zoom lens. The main unit holds the lens guiding frame to be movable in a direction of an optical axis with the zoom lens. The position detecting device detects a position of the zoom lens held in the main unit. The position detecting device includes an optical sensor and a detection target member. The detection target member includes a sensor cut unit and a sensor cover unit. The sensor cut unit is detected by the optical sensor. The sensor cover unit covers the optical sensor and the sensor cut unit during the detection.