A heat exchanger includes tubes having tube inlets, an inlet tank having therein an inlet tank space, and a dynamic baffle disposed in the inlet tank space. The inlet tank has a tank inlet. The tubes include first tubes and second tubes. The first tubes are closer to the tank inlet than the second tubes are to the tank inlet. The first tubes include a nearest tube that is, among the tubes, closest to the tank inlet. The dynamic baffle is configured to, when the fluid pressure of the thermal fluid in the inlet tank space is below a specified value, suppress the flow rates of the plurality of first tubes, and, when the fluid pressure of the thermal fluid in the inlet tank space is at or above the specified value, increase the flow rate of at least one of the plurality of the first tubes.