Provided is a metal-clad laminated board comprising an insulating layer and a metal layer that is in contact with at least one surface of the insulating layer, and the insulating layer contains a cured product of a thermosetting resin composition that contains a product of a reaction between a poly(phenylene ether) having an average of 1.5-2 hydroxyl groups per molecule and an epoxy compound having an average of 2-2.3 epoxy groups per molecule. The reaction product has a terminal hydroxyl group concentration of 700 [mu]mol/g or less, the metal layer is provided with a metal base material and acobalt-containing barrier layer provided on at least the surface of the metal base material that is in contact with the insulating layer, and the surface roughness of the contact surface is such thatthe ten-point average roughness Rz is 2 [mu]m or less.