To provide a heating-element cooling device for a vehicle easily installed in a vehicle.

A branch section 31 is disposed in a back seat vent duct 30 connected to an air conditioner AC, and is connected to a battery cooling duct 50 connected to a battery case 60. The branch section 31 is provided with a changeover door 35, and the battery cooling duct 50 is provided with a normally/reversely rotatable fan 51. When the changeover door 35 is driven to a turning position where air can be fed to both a downstream duct 30b and a battery cooling duct 50, and the fan 51 is driven to the normal rotation, air-conditioning air can be fed to the downstream duct 30b and the battery cooling duct 50. An upstream duct 30a is closed by the changeover door 35, and the air in the cabin can be sucked from a back seat vent port 34 by the fan 51 and fed to a battery 61.