A Wiring substrate includes a substrate body that is formed from ceramics, and that includes a front surface, a back surface, and side surfaces positioned between peripheral sides of the front surface and the back surface; a frame-shaped metalized layer (surface conductor portion) that is formed on the front surface of the substrate body, a surface of the frame-shaped metalized layer being covered with a metal plating film; and an electroplating conductor layer that is formed in the substrate body, an end of the electroplating conductor layer being electrically connected to the frame-shaped metalized layer, the other end of the electroplating conductor layer being formed at the front surface of the substrate body, the other end of the electroplating conductor layer being electrically independent of different conductor portions that differ from frame-shaped metalized layer, the electroplating conductor layer being separated from the side surfaces of the substrate body. An opening portion for exposing at least a portion of the electroplating conductor layer at a bottom surface is formed in the front surface of the substrate body.