a wiring substrate includes : a substrate layer made of glass or silicon and including : a first surface formed with a first hole ; and a second surface formed with a second hole and being opposite to the first surface , wherein the first hole is communicated with the second hole ; a connection pad formed in the second hole ; a first wiring layer formed in the first hole and electrically connected to the connection pad ; a first insulation layer formed on the first surface of the substrate layer to cover the first wiring layer ; and a second wiring layer formed on the first insulation layer and electrically connected to the first wiring layer . a diameter of the first hole is gradually decreased from the first surface toward the second surface , and a diameter of the second hole is gradually decreased from the second surface toward the first surface .