A method for fabricating a phase shift mask includes obtaining a layout of a mask region which sets up alight transmitting region; obtaining a layout of a phase shift region placed in a border portion of the mask region by disposing a shadow core region for light-shielding in a middle portion of the mask region; forming phase shift patterns following the layout of the phase shift region on a light transmitting substrate; and forming a shadow core layer pattern which exposes a portion of the substrate corresponding to the light transmitting region between the phase shift patterns and covering and light-shielding the portion of the substrate corresponding to the shadow core region, and a mask fabricated by the method.