An antenna device, a feeding cable module thereof, and a metallic cable holder are provided. The metallic cable holder includes two fixing portions and a cable arrangement portion. The two fixing portions are arranged along a straight direction and are fixed onto a metal plate. The cable arrangement portion is connected between the two fixing portions and includes a plurality of rack segments regularly arranged along the straight direction. Each of the rack segments has an insertion opening, and the insertion opening of each of the rack segments is configured to hold a feeding cable having a cable diameter that is greater than an opening diameter of the insertion opening. When the feeding cable passes through the insertion opening to be positioned by the corresponding rack segment, the feeding cable is surrounded by the corresponding rack segment with a predetermined angle that is smaller than 360 degrees.