An apparatus of auto-focusing is provided, including an outer holder, a wire set, a magnet set and an inner-holder. The magnet set is fixed at the corners inside the outer-holder. The inner-holder is a hollow cylinder surrounded by a coil. The wire set is connected to the top and the bottom ends of the outer-holder. The other end of the wire set is connected to the outer circumference of the inner-holder. Therefore, the inner-holder is a hanging moveable component, which can move vertically when the electrical current flows through the coil to achieve the object of auto-focusing.