Disclosed is a washing machine, a control panel assembly of which has an improved structure to minimize problems caused by a shaking of a rotary knob and the interference of the rotary knob with other surrounding parts. The control panel assembly of the washing machine includes a control panel, a knob guide installed on the control panel, and a rotary knob rotatably mounted on the knob guide and including a boss passing through the knob guide. The knob guide includes a boss insertion part restricting the boss to prevent the rotary knob from shaking. The boss insertion part includes an extension extended from the bottom surface of the knob guide and forming a boss insertion hole, into which the boss is inserted, therein.