To cool the entire heat producing face of a heat producing device to enhance efficiency in cooling and thus save power by jetting cooling fluid in proximity to the heat producing face and vibrating the fluid parallel to the heat producing face in a required range.

A jet stream of cooling fluid is jetted out of a jet stream generating means 2 and made to impinge on the heat producing device 1 mounted on a circuit board 15 to cool the heat producing face 1a of the heat producing device 1. The jet of the cooling fluid jetted out of a jetting port 3 becomes a jet stream which is made to impinge on the heat producing face 1a of the heat producing device 1 and the point of collision is a stagnation point (a). At the stagnation point the thermal conductivity is maximized to accelerate thermal conduction and accomplish cooling. So the jet stream generating means 2 is vibrated parallel to the heat producing face 1a of the heat producing device 1 and thereby the stagnation point a arising from the jet of the cooling fluid is moved in a required range. As a result, thermal conduction is accelerated throughout the heat producing face 1a.