A lens module using electromagnetic force to drive the focus-adjusting lens is disclosed. The lens module includes a base, two steel plates, four springs, a bottom plate, a lens holder, a coil, a lens, a top plate, two magnets, a magnet housing and a top cover. The lens holder, the coil and the top plate are disposed outside the circumference of the lens to form a linked body and the coil is clipped between the lens holder and the top plate so as to reduce diameter and volume of the coil. By the two arc magnets disposed on right and left sides of the coil instead of general circular magnets, volume of the magnets is reduced. By the four springs vertically hooked between four corners of two steel plates respectively and four corresponding brackets of the lens holder, the lens is provided with axial traction for focus adjustment. Therefore, the lens with smaller volume moves steadily to adjust the focus.