A heat sink comprising a heat receiving plate and at least one piece of heat radiating fin stacked on the heat receiving plate, wherein slits which penetrate the heat radiating fin from the upper to lower surface are formed on a flat plate surface of the heat radiating fin, and a plurality of fin protrusions are provided in a portion on the flat plate surface where the slits are not formed, and all the fin protrusions or a portion of the fin protrusions of the stacked heat radiating fin are disposed at different positions on the heat radiating fin so that an interval between the heat receiving plate and heat radiating fin, or an interval between the stacked heat radiating fins is maintained by the fin protrusions.