There is provided a package substrate capable of controlling the degree of warpage thereof by improving the composition and formation of a post terminal and a method of fabricating the same. The package substrate includes a substrate having at least one conductive pad; an insulating layer provided on the substrate and having an opening to expose the conductive pad; a separation barrier layer provided on the conductive pad inside the opening and formed to be higher than the upper surface of the insulating layer along the side walls thereof; a post terminal provided on the separation barrier layer; and a solder bump provided on the post terminal.