A circuit board provided with a first resin layer and with a first conductive layer formed on the first resin layer. The first conductive layer has a metal carbide layer containing a carbide of a transition metal selected from Group IV, Group V, or Group VI in the Periodic Table and bonded to the first resin layer. The first resin layer has a first region to which the metal carbide layer is bonded and a second region located in an inner portion of the first resin layer from the first region. The first region has a larger ratio of number of atoms of nitrogen relative to number of atoms of carbon than in the second region.