A method of operating a washing machine having a pulsator rotatably provided in a tub , the method comprising a first cleaning mode (M100) and a second cleaning mode (M200), wherein the first cleaning mode (M100) comprises: a first process (M110) of rotating the pulsator in one direction with a first angle (A1) and then rotating it in the other direction with a second angle (A2) around a rotation shaft ; and a second process (M120) of rotating the pulsator in the one direction with a third angle (A3) and then rotating it in the other direction with a fourth angle (A4) around the rotation shaft , wherein the second cleaning mode (M200) comprises: a process in which the pulsator alternately performs forward and reverse rotations with a predetermined angle (A0) around the rotation shaft , wherein the first angle (A1) is greater than the third angle (A3), and the second angle (A2) is greater than the fourth angle (A4), and the second angle (A2) is greater than the third angle (A3), wherein the first angle (A1) and the second angle (A2) are greater than the predetermined angle (A0), and the third angle (A3) and the fourth angle (A4) are less than the predetermined angle (A1), wherein the first cleaning mode (M100) alternately implements the first process (M110) and the second process (M120) at least twice, and wherein the predetermined angle (A0) is 720°. a first process (M110) of rotating the pulsator in one direction with a first angle (A1) and then rotating it in the other direction with a second angle (A2) around a rotation shaft ; and a second process (M120) of rotating the pulsator in the one direction with a third angle (A3) and then rotating it in the other direction with a fourth angle (A4) around the rotation shaft , wherein the second cleaning mode (M200) comprises: a process in which the pulsator alternately performs forward and reverse rotations with a predetermined angle (A0) around the rotation shaft , wherein the first angle (A1) is greater than the third angle (A3), and the second angle (A2) is greater than the fourth angle (A4), and the second angle (A2) is greater than the third angle (A3), wherein the first angle (A1) and the second angle (A2) are greater than the predetermined angle (A0), and the third angle (A3) and the fourth angle (A4) are less than the predetermined angle (A1), wherein the first cleaning mode (M100) alternately implements the first process (M110) and the second process (M120) at least twice, and wherein the predetermined angle (A0) is 720°. a process in which the pulsator alternately performs forward and reverse rotations with a predetermined angle (A0) around the rotation shaft , wherein the first angle (A1) is greater than the third angle (A3), and the second angle (A2) is greater than the fourth angle (A4), and the second angle (A2) is greater than the third angle (A3), wherein the first angle (A1) and the second angle (A2) are greater than the predetermined angle (A0), and the third angle (A3) and the fourth angle (A4) are less than the predetermined angle (A1), wherein the first cleaning mode (M100) alternately implements the first process (M110) and the second process (M120) at least twice, and wherein the predetermined angle (A0) is 720°. <EOS>