A wiring substrate includes a core, a first wiring layer formed on a first surface of the core, and a second wiring layer formed on a second surface of the core. The first wiring layer includes a first opening, and the second wiring layer includes a second opening. The core includes a plurality of electronic component accommodating bores that extend through the core at portions exposed from the first and second openings. An electronic component is arranged in each electronic component accommodating bore. The electronic component accommodating bores are filled with an insulating layer. The core includes a partition located between adjacent electronic component accommodating bores. The partition is formed by part of the core.