HEAT SINK

A heat sink includes: a container in which a cavity is formed, the container having a first principal surface and a second principal surface; a working fluid encapsulated in the cavity, and a steam flow path defined in the cavity, in which the container has a flat portion and a protruding part projecting from the flat portion, an inner space of the protruding part of the container is in communication with an inner space of the flat portion to form the cavity, the protruding part of the container includes a heat receiver that is to be thermally connected with a heating element that is a cooling target, and the flat portion of the container has an intermediate portion region continuous from the protruding part and a heat radiator region more distant from the protruding part than the intermediate portion region and thermally connected with a heat radiating fin.