In a thermal management system for a battery electric vehicle, a controller is configured to, in a heating mode, control a switching valve to select a first valve position when a power supply temperature is higher than a predetermined power supply temperature threshold, and control the switching valve to select a second valve position when the power supply temperature is equal to or lower than the power supply temperature threshold. The controller is configured to switch the switching valve from the first valve position to the second valve position regardless of the power supply temperature, when a temperature of a heat medium that has passed through a power supply cooler is lower than an outside air temperature by a predetermined margin temperature difference or more while the switching valve is in the first valve position.