The reservoir tank includes: a tank body that stores cooling fluid; an inflow pipe for feeding the cooling fluid into the tank body; and a discharge pipe for discharging the cooling fluid from the tank body, in which the tank body has at least one tank chamber, a discharge port is provided in a bottom surface of the tank chamber or at a position adjacent to the bottom surface, the discharge pipe is connected to the discharge port, and a shield is disposed above the discharge port so as to cover the discharge port in a plan view.