The present disclosure provides a heatsink that can increase a fin area of a heat radiating fin while securing sufficient volumes of a heat receiving portion, heat insulating portion, and heat radiating portion even in an environment in which an installation space for the heatsink, more specifically, an installation space in a height direction of the heatsink is limited.
A heatsink including: a heat transport member having a heat receiving portion thermally connected to a heating element; a pipe body connected to a heat radiating portion of the heat transport member; and a heat radiating fin group which is thermally connected to the pipe body and in which a plurality of heat radiating fins is arranged, wherein the heat transport member has an integral internal space that communicates from the heat receiving portion to a connection portion with the pipe body and that is filled with a working fluid, the internal space of the heat transport member communicating with an internal space of the pipe body, and a cross-sectional area of an internal space in a direction orthogonal to a heat transport direction of the heat transport member in the heat radiating portion is smaller than the cross-sectional area in a heat insulating portion between the heat receiving portion and the heat radiating portion.