The invention relates to a circuit board (20) onto which an electronic component is to be mounted, and a manufacture method for the circuit board. The circuit board (20) is provided with insulating core substrates (40, 60) and patterned metal sheets. The metal sheets (50, 70) are bonded to at least one surface of the insulating core substrates (40, 60). The insulating core substrates (40, 60) and the metal sheets (50, 70) form a layered body (S1) in which a gas venting hole is provided. The gas venting hole is formed so that when the electronic component (80) is mounted, the gas present between the insulating core substrates (40, 60) and the metal sheets (50, 70) expands and is released to the open air side via the gas venting hole.