Abstract: A washing machine includes a washing and water-extracting tub, agitating blades disposed rotatably in the tub, a motor for rotating the tub or the agitating blades and a control unit for controlling operation of the motor and determining a quantity of clothes on the basis of a resistance of the clothes exerted on the agitating blades by the rotation of the agitating blades. The washing machine determines the quantity of clothes plural times while a water level is changed from a low water level to a high water level and makes calculation on the basis of the plurality of determination values to determine a kind of clothes or the quality of cloth so that the washing operation is controlled on the basis of the quantity of clothes and the determined quality of cloth.