A method of refining molten metal with stirring in a refining vessel by repeated operation of suction and discharge is disclosed, wherein a lower end of a refractory cylinder is immersed into a molten metal bath in the vessel and an inside of the cylinder opposite to the immersed end is alternately subjected to evacuation and pressurization. In this method, maximum and average values of pressure reduction velocity to be applied to the inside of the cylinder are limited to not more than 1,000 mmHg/sec and not more than 500 mmHg/sec, respectively, and an evacuation time is extended over at least 1.5 times intrinsic oscillation period of up and down movement of molten metal column inside the cylinder.