Disclosed herein is a method of manufacturing a heat radiation substrate, including injection-molding mixed powder of carbon nanotubes and metal in a die to fabricate a metal core having through holes; molding the entire metal core including the through holes with an insulating resin to fabricate a metal core substrate; processing the insulating resin provided in the through holes to form connection holes; and forming a circuit pattern on the metal core substrate in which the connection holes are formed.