The present invention relates to an operation method of a washing machine for controlling the rotation of a pulsator to enhance cleaning performance, there is provided a method of operating a washing machine having a pulsator rotatably provided in a tub, and the method may include a first cleaning mode having a first process of rotating the pulsator in one direction at a first angle and then rotating it in the other direction at a second angle around the rotation shaft; and a second process of rotating the pulsator in the one direction at a third angle and then rotating it in the other direction at a fourth angle around the rotation shaft, wherein the first angle is greater than the third angle, and the second angle is greater than the fourth angle, and the second angle is greater than the third angle.