Disclosed is a washing machine having an improved structure of enabling laundry to be put into the washing machine without restraint, the washing machine including a cabinet forming an external appearance of the washing machine, and provided at a front side thereof with an inlet port, a tub provided in the cabinet and accommodating wash water, a drum rotatably provided in the tub, and a door installed at the cabinet to open and close the inlet port, wherein the door is provided with a subsidiary door that is freely open and closed independent of the door during a washing cycle.