A control device used for a computer casing on which a plurality of expansion cards is inserted, is composed of a first frame and a second frame which are installed in a casing of height of 2U; a connection element, which is connected on the first and second frames, and is in a vertical state; a right riser card, which is connected on a right side of the connection element; a left riser card, which is connected on a left side of the connection element; a plurality of expansion cards, which is inserted horizontally into a plurality of slots of the right riser card; and a plurality of expansion cards, which is inserted horizontally into a plurality of slots of the left riser card. By this control device, at least more than seven expansion cards or interface cards can be inserted.