An aqueous urea solution supply device for an internal combustion engine including an exhaust passage, the aqueous urea solution supply device being characterized by comprising: a tank that stores aqueous urea solution; an urea adding valve configured to be disposed on the exhaust passage, the urea adding valve being configured to add the aqueous urea solution to exhaust gas of the internal combustion engine; an aqueous urea solution passage being configured to supply the aqueous urea solution from the tank to the urea adding valve; a pump disposed on the aqueous urea solution passage; a pressure detection device configured to detect a pressure of the aqueous urea solution supplied to the urea adding valve; a water quantity detection device configured to detect an aqueous urea solution amount in the tank, and an electronic control unit configured to execute a return control, the return control being a control for returning the aqueous urea solution from the urea adding valve to the tank when the electronic control unit determines that the aqueous urea solution in an addition amount required for cooling of the urea adding valve is not supplied from the tank to the urea adding valve, the electronic control unit being configured to determine that the aqueous urea solution in the addition amount required for the cooling of the urea adding valve is not supplied from the tank to the urea adding valve when the pressure of the aqueous urea solution detected by the pressure detection device is equal to or lower than a predetermined pressure (PNTS) and the aqueous urea solution amount detected by the water quantity detection device is equal to or smaller than a predetermined threshold (RNTS). a tank that stores aqueous urea solution; an urea adding valve configured to be disposed on the exhaust passage, the urea adding valve being configured to add the aqueous urea solution to exhaust gas of the internal combustion engine; an aqueous urea solution passage being configured to supply the aqueous urea solution from the tank to the urea adding valve; a pump disposed on the aqueous urea solution passage; a pressure detection device configured to detect a pressure of the aqueous urea solution supplied to the urea adding valve; a water quantity detection device configured to detect an aqueous urea solution amount in the tank, and an electronic control unit configured to execute a return control, the return control being a control for returning the aqueous urea solution from the urea adding valve to the tank when the electronic control unit determines that the aqueous urea solution in an addition amount required for cooling of the urea adding valve is not supplied from the tank to the urea adding valve, the electronic control unit being configured to determine that the aqueous urea solution in the addition amount required for the cooling of the urea adding valve is not supplied from the tank to the urea adding valve when the pressure of the aqueous urea solution detected by the pressure detection device is equal to or lower than a predetermined pressure (PNTS) and the aqueous urea solution amount detected by the water quantity detection device is equal to or smaller than a predetermined threshold (RNTS).