To solve problems of prior cooling device for water container using a Peltier element which has a poor cooling efficiency due to cooled water is warmed in passing through a conveying pump or the like, and it requires a large power and is expensive, big and heavy.

This water cooling device comprises a cooling member 12 soaked in water installed on one side of a Peltier element, a heat sink 13 for heat radiation installed on the other side of the element through an aluminum plate 14 for promoting heat radiation and a heat radiating fan 15 installed on the heat sink 13, and the device cools water W of a water tank for an aquatic animal or a water container 30 for a cooler or the like for a live bait.