A method for manufacturing a wiring substrate includes the steps of: (a) forming a sacrificial layer in a first pattern on a substrate; (b) forming a catalyst layer in a second pattern on the substrate; (c) immersing the substrate in an electroless plating liquid, thereby depositing a metal layer on the catalyst layer in the second pattern; and (d) heating to remove the sacrificial layer and to form a metal layer in a third pattern, wherein the third pattern is a region where the first pattern and the second pattern overlap each other.