A wiring board includes a resin substrate in which reinforcement members are arranged horizontally, a through electrode filled in a through hole penetrating the substrate in a thickness direction, and wiring layers respectively formed on both surfaces of the substrate and electrically connected to each other via the through electrode. The reinforcement members are arranged such that reinforcement members arranged in a middle region of the substrate in the thickness direction has higher density than reinforcement members arranged in the regions other than the middle region of the substrate.