Embodiments of the invention provide an interconnect substrate capable of improving the connection reliability and yield of a semiconductor device, a method of manufacturing the interconnect substrate, and a semiconductor device using the interconnect substrate. An interconnect substrate according to an embodiment of the invention includes: a substrate; an electrode pad formed over the substrate; an insulating film (solder resist film) formed over the substrate; an opening formed in the insulating film, in which the upper surface of the electrode pad is exposed on the bottom surface of the opening and a metal film formed over the upper surface of the electrode pad and side surface of the insulating film in the opening. At least a portion of the edge of an upper surface of the metal film is higher than the other portions of the upper surface of the metal film.