A cooling apparatus for an internal combustion engine, the cooling apparatus comprising: a circulation circuit for coolant flowing through the internal combustion engine; a pump arranged on the circulation circuit, the pump being configured to change a discharge amount of coolant; a flow rate adjustment valve arranged on the circulation circuit in series with the pump; and a controller configured to control a pump discharge amount that is the discharge amount of coolant in the pump, wherein the flow rate adjustment valve includes a valve member configured to rotate to change an open degree of the flow rate adjustment valve, and a stopper that moves between a restriction position at which the stopper engages with the valve member to restrict rotation of the valve member and a retraction position at which the stopper does not engage with the valve member and the rotation of the valve member is permitted, the valve member is configured to rotate in a valve-opening direction that is a rotation direction in which the open degree increases when a pressure difference increases between a position upstream of the valve member and a position downstream of the valve member in a flow direction of coolant in the circulation circuit and rotate in a valve-closing direction that is a rotation direction in which the open degree decreases when the pressure difference decreases, and the controller is configured to execute, when maintaining the open degree, a preparatory process of moving the stopper to the restriction position after arranging the stopper at the retraction position and arranging the valve member further in the valve-closing direction than the stopper through control of the pump discharge amount. a circulation circuit for coolant flowing through the internal combustion engine; a pump arranged on the circulation circuit, the pump being configured to change a discharge amount of coolant; a flow rate adjustment valve arranged on the circulation circuit in series with the pump; and a controller configured to control a pump discharge amount that is the discharge amount of coolant in the pump, wherein the flow rate adjustment valve includes a valve member configured to rotate to change an open degree of the flow rate adjustment valve, and a stopper that moves between a restriction position at which the stopper engages with the valve member to restrict rotation of the valve member and a retraction position at which the stopper does not engage with the valve member and the rotation of the valve member is permitted, a valve member configured to rotate to change an open degree of the flow rate adjustment valve, and a stopper that moves between a restriction position at which the stopper engages with the valve member to restrict rotation of the valve member and a retraction position at which the stopper does not engage with the valve member and the rotation of the valve member is permitted, the valve member is configured to rotate in a valve-opening direction that is a rotation direction in which the open degree increases when a pressure difference increases between a position upstream of the valve member and a position downstream of the valve member in a flow direction of coolant in the circulation circuit and rotate in a valve-closing direction that is a rotation direction in which the open degree decreases when the pressure difference decreases, and the controller is configured to execute, when maintaining the open degree, a preparatory process of moving the stopper to the restriction position after arranging the stopper at the retraction position and arranging the valve member further in the valve-closing direction than the stopper through control of the pump discharge amount.