A wiring substrate includes: a plate-like base material containing carbon fibers; a wiring layer formed on a surface of the base material; a first via including a first through hole penetrating through the base material, a first resin layer formed on an inner wall of the first through hole and including a second through hole, and a first conductive layer formed on an inner wall of the second through hole; and a second via including a third through hole penetrating through the base material and a second conductive layer formed on an inner wall of the third through hole, wherein an inside diameter of the third through hole is greater than an inside diameter of the second through hole.