An optical device. At least one guide bar is connected to a base. A coil is disposed in the base. A central axis of the coil in an optical axis direction of the optical device is parallel to a central axis of the guide bar in the optical axis direction. A lens housing is slidably fitted on the guide bar. A central axis of the lens housing in the optical axis direction is parallel to that of the guide bar. The lens housing slides along the central axis of the guide bar. A magnetic member is connected to the lens housing opposite the coil, providing a first magnetic field. When the coil is energized to generate a second magnetic field, the lens housing slides on the guide bar by attraction or repulsion of the first and second magnetic fields.