PURPOSE: To provide a board for mounting electronic parts which can prevent the outflow of a mount material and besides is excellent in heat radiation and moisture resistance, and its manufacture.

CONSTITUTION: This device has an insulating board 79 provided with a mount for electronic parts and a plurality of heat conductive holes 75 which are provided below the mount 70 for electronic parts and besides pierce the insulating board 70. The inwall of the heat conductive holes 75 is covered with a metal- plated film 5. It is to be desired that the topside and the underside of the heat conductive hole 75 should be covered with metal-plated films 55. The heat conductive hole 75 opened to the mount 70 for electronic parts is covered with, for example, a mount material 6.