According to one embodiment, a heat sink includes first and second fin units. Fins of the first fin unit are provided with a through-hole part in which a heat pipe is inserted. Fins of the second fin unit are provided with a cutout part cut out to avoid the heat pipe. The fins of the second fin unit are inserted in spaces between the fins of the first fin unit. The fins of the second fin unit reach to a region in which the fins of the second fin unit overlap the heat pipe in the first fin unit.