An exemplary camera module includes a lens holder (10), a lens module (20), a position detecting mechanism (30), and an image pick-up module (40). The lens module includes a lens barrel (11) and one lens received in the lens barrel. The lens barrel is axially movable received in the lens holder. The position detecting mechanism includes a conductive strip (32) disposed on outer periphery of the lens barrel along an axial direction, a number of conductive terminals (36), a number of electrical sources (34), and a processor (38). The conductive terminals are securely arranged on an inner periphery of the lens holder parallel to each other. A cathode of each electrical source is electrically connected to a corresponding conductive terminal. The processor is electrically connected with an anode of each electrical source. The image pick-up module is arranged so as to receive the light from the lens module.