A heat transfer device couples a heat generation member with a heat radiation member, and transfers heat from the heat generation member to the heat radiation member. The heat transfer device includes a composite member and a heat conductor. The composite member includes multiple carbon nanotubes and multiple carbon fibers which are mixed into a base material and complexed together, and the respective carbon fibers are crosslinked with each other by the carbon nanotubes. The heat conductor has one flexible end embedded in the composite member. The embedded one end is crosslinked with the carbon fibers in the composite member through the carbon nanotubes.