Disclosed is a method for forming a capacitor of a semiconductor device. In such a method, a mold insulating layer is formed on an insulating interlayer provided with a storage node plug, and the mold insulating layer is etched to form a hole through which the storage node plug is exposed. Next, a metal storage electrode with an interposed WN layer is formed on a hole surface including the exposed storage node plug and the mold insulating layer is removed. Finally, a dielectric layer and a plate electrode are formed in order on the metal storage electrode.