A thermal management device includes a first thermal circuit, a second thermal circuit, and a control unit. The first thermal circuit includes a first radiator and a battery. The second thermal circuit includes a heater, a temperature sensor, a first path, a second radiator, a second path, a heating appliance, and a flow rate adjusting unit. When a battery heating request and an air heating request are made, the control unit heats a second thermal transfer medium, and divides the flow of the second thermal transfer medium to the first and second paths. When a deficiency value of measured temperature with respect to a target temperature of the second thermal transfer medium is greater than a first threshold value in flow dividing processing, a second flow dividing proportion of the second path is set to be greater than a first flow dividing proportion of the first path.