A lens device includes a base, a lens unit, a dividing plate, a cover plate, a shutter unit, and an actuator unit. The base has a front section with a front surface, a rear section with a rear surface, a lens hole, and a mounting space. The lens unit is disposed in the lens hole, and includes a lens. The dividing plate is mounted on the front section and has a first light hole. The cover plate is mounted on the front section and has a second light hole. The dividing plate and the cover plate define a working space therebetween. The shutter unit includes a first shutter piece pivotally disposed in the working space. The actuator unit is mounted in the mounting space, and includes a rotation portion, and an operating portion formed on the rotation portion and extending into the working space.