A camera module includes a lens holder, a lens module, an image sensor chip, and a PCB defining a step-shaped recess on the upper thereof. The step-shaped recess comprises a first recess formed on an upper portion thereof and a second recess, for receiving a plurality of electrical elements therein, coaxially formed on a lower portion thereof, and a intermediate step surface formed between the first recess and the second recess. A cover plate received in the first recess and attached on the intermediate step surface defines at least one electronic layer therein and an external point formed on the bottom thereof. At least one zero voltage point is formed on the intermediate step surface thereof. The electronic layer is electrically connected to the zero voltage points by the external points, thereby electromagnetic waves generated by the electronic elements are prevented from affecting the image sensor chip.