Abstract: The present invention relates to a chip-type protection device having an enclosed micro-gap between electrodes. The invention includes a substrate on which a pair of discharge electrodes extend towards each other by a micro-gap. A wall is disposed in a manner spaced apart from the micro-gaps by a predetermined distance, on which a cover portion is mounted in a straddling manner across the micro-gaps. The wall and the cover portion are integrated under a predetermined gaseous environment to form a hermectic chamber on which an outer protective layer is coated. End electrodes are subsequently formed on the substrate in a manner connected to conductive portions of the discharge electrodes. The invention provides a protection device against over-voltage.