A multilayer heat sink that cools an object in contact with the heat sink by flowing a fluid from a fluid inlet to a fluid outlet, the heat sink comprising: a heat-receiving layer having a top surface in contact with the object to receive heat; a channel layer (20, 20a, 20b, 20c) provided on a bottom surface of the heat-receiving layer, the channel layer including cooling micropaths (28, 28a, 28b, 28c, 28d) extending and directing the fluid in a direction orthogonal to a stacking direction; an orifice layer (22, 22a, 22b) provided on a bottom surface of the channel layer, the orifice layer including: jet orifices (30, 30a, 30b, 30c) configured to jet the fluid into the cooling micropaths from the bottom surface; and drain orifices (32, 32a, 32b, 32c) configured to drain the fluid from the cooling micropaths toward the bottom surface; a header layer provided on a bottom surface of the orifice layer, the header layer including: a peripheral wall; and a baffle provided in a region surrounded by the peripheral wall, the baffle being configured to separate the fluid inlet from the fluid outlet; and a bottom layer provided on a bottom surface of the header layer, wherein the baffle includes: parallel plates disposed parallel to each other; and end plates (40, 42) configured to alternately close an opening at an end and an opening at an opposite end of the parallel plates, and the orifice layer, the bottom layer, the baffle, and the peripheral wall define a supply channel to guide the fluid from the fluid inlet to the jet orifices and a drain channel to guide the fluid from the drain orifices to the fluid outlet. a heat-receiving layer having a top surface in contact with the object to receive heat; a channel layer (20, 20a, 20b, 20c) provided on a bottom surface of the heat-receiving layer, the channel layer including cooling micropaths (28, 28a, 28b, 28c, 28d) extending and directing the fluid in a direction orthogonal to a stacking direction; an orifice layer (22, 22a, 22b) provided on a bottom surface of the channel layer, the orifice layer including: jet orifices (30, 30a, 30b, 30c) configured to jet the fluid into the cooling micropaths from the bottom surface; and drain orifices (32, 32a, 32b, 32c) configured to drain the fluid from the cooling micropaths toward the bottom surface; jet orifices (30, 30a, 30b, 30c) configured to jet the fluid into the cooling micropaths from the bottom surface; and drain orifices (32, 32a, 32b, 32c) configured to drain the fluid from the cooling micropaths toward the bottom surface; a header layer provided on a bottom surface of the orifice layer, the header layer including: a peripheral wall; and a baffle provided in a region surrounded by the peripheral wall, the baffle being configured to separate the fluid inlet from the fluid outlet; and a peripheral wall; and a baffle provided in a region surrounded by the peripheral wall, the baffle being configured to separate the fluid inlet from the fluid outlet; and a bottom layer provided on a bottom surface of the header layer, wherein the baffle includes: parallel plates disposed parallel to each other; and end plates (40, 42) configured to alternately close an opening at an end and an opening at an opposite end of the parallel plates, and parallel plates disposed parallel to each other; and end plates (40, 42) configured to alternately close an opening at an end and an opening at an opposite end of the parallel plates, and the orifice layer, the bottom layer, the baffle, and the peripheral wall define a supply channel to guide the fluid from the fluid inlet to the jet orifices and a drain channel to guide the fluid from the drain orifices to the fluid outlet.