A wiring board includes a substrate having an opening portion, multiple electronic devices positioned in the opening portion such that the electronic devices are arrayed in the lateral direction of each of the electronic devices, and an insulation layer formed on the substrate such that the insulation layer covers the electronic devices in the opening portion of the substrate. The substrate has a wall surface defining the opening portion and formed such that the opening portion is partially partitioned and the electronic devices are kept from making contact with each other.