To provide a cooling device of a battery which efficiently cools the battery.

A battery 29 is formed by a battery element part 11 and a housing case 12 housing the battery element part 11. A Peltier element 13 serving as a cooler is provided at a gravity direction upper part of the housing case 12, and a container 14 accumulating a liquid F, causing convention flow in a free space of corners in the housing case 12, is provided. Heat generated from the battery element part 11 is radiated and cooled by being transmitted to a heat absorption part 13A of the Peltier element 13 through a winding end part 11A of the battery element part 11 and through an outer peripheral surface 11C of the battery element part 11 and the liquid F.