<p>A heat medium cooling device is provided with: a means for exchanging heat between a heat medium and liquid nitrogen through a partition; a means for supplying liquid nitrogen to the heat medium-side region of the heat exchange means; a means for supplying liquid nitrogen to the liquid nitrogen-side region of the heat exchange means; a means for adjusting the amount of the liquid nitrogen supplied to the heat medium-side region of the heat exchange means; and a means for adjusting the amount of the liquid nitrogen supplied to the liquid nitrogen-side region of the heat exchange means.</p>
