A printed board is able to cool an electronic component with high efficiency without requiring a heatsink for cooling the electronic component while preventing upsizing of the electronic device. A method for manufacturing such a printed board with high efficiency is also disclosed. Since a carbon layer principally made of carbon and having excellent heat conductivity is provided inside an insulator or on a surface of the insulator in a laminated form, heat generated by the electronic component when the electronic component is energized is conducted to the carbon layer, diffused through the carbon layer, and then radiated to the outside. Therefore, the heat generated by the electronic component can be reliably radiated by heat conduction to the carbon layer and heat diffusion through the carbon layer, thereby cooling the electric component with high efficiency.