A method of making a wiring substrate having at least one interconnection layer includes forming a first metal layer on a surface of a support member having at least one columnar through hole that exposes the surface of the support member, forming a columnar metal layer that fills the columnar through hole, forming an insulating layer on the columnar metal layer and on the first metal layer, forming an interconnection layer on a first surface of the insulating layer electrically connected to the columnar metal layer through the insulating layer, and forming, by removing at least an entirety of the support member and an entirety of the first metal layer, a protruding part including at least part of the columnar metal layer protruding from a second surface of the insulating layer opposite the first surface, and serving as at least part of a connection terminal of the wiring substrate.