Cooling water control apparatus for internal combustion engine

The cooling water control apparatus of the disclosure includes: a cooling water circuit; a heat accumulator which is arranged in the cooling water circuit and stores high-temperature cooling water flowing out from an internal combustion engine; an on-off valve for opening/closing the cooling water circuit; a heater passage which is connected in parallel to the cooling water circuit; and a flow rate control valve which controls a flow rate of the cooling water inside the heater passage. The cooling water inside the heat accumulator is supplied to the internal combustion engine by closing the flow rate control valve and opening the on-off valve in order to promote warm-up at the start of the internal combustion engine, and thereafter, the on-off valve is closed, and an opening degree of the flow rate control valve is controlled to make the temperature of the internal combustion engine reach a specified target temperature.