Heating a battery and cooling an electric power conversion device are achieved together. This mobile body includes an electric motor, a battery, a thermoelectric conversion element, an electric power conversion device, and a controller. The electric motor is a driving source. The electric power conversion device is configured to convert electric power outputted from the battery into driving electric power for the electric motor. The electric power conversion device is disposed in direct contact or in indirect contact with the battery with the thermoelectric conversion element interposed therebetween. The controller is configured to control electric power to be supplied to the thermoelectric conversion element. The controller controls, in a case where the battery is in a predetermined low-temperature state, the electric power to be supplied to the thermoelectric conversion element to cause a surface of the thermoelectric conversion element coupled to the battery to serve as a heat dissipation surface.