Provided is a method for producing a heat sink that can easily and effectively form a heat radiating film on the surface of a substrate without requiring enormous heat energy for increasing the temperature of the substrate. The method is a method for producing a heat sink having a substrate and a heat radiating film formed on the surface of the substrate, including a first step of casting a substrate by injecting molten metal into a cavity of molding dies; and a second step of applying a heat radiating coating to the substrate through spraying or dropping in the period from when the molding dies are opened after the casting until when the temperature of the substrate that has been cast becomes lower than the deposition temperature that is a temperature necessary to deposit the heat radiating coating on the substrate.