A drum-type washing machine, comprising: a washing tank that rotates while accommodating clothes; an outer tank that mounts the washing tank; a water intake port which is connected to a lowermost portion of the outer tank, wherein a circulation route is communicated with the water intake port and a circulation pump is provided in the circulation route; a driving unit that drives the washing tank wherein the washing water taken from the water intake port is ejected to the washing tank from an ejection port through the circulation route; a water supply valve that is configured to sequentially fill the outer tank and the washing tank with water; a contamination sensor that senses contamination of washing water in the outer tank; and a controller that controls the driving unit by determining a degree of the contamination based on an output of the contamination sensor, characterized in that when the clothes are put in the washing machine, the controller is configured to sense an amount of the clothes; then, the controller is configured to set a water level based on the amount of the clothes; then, the controller is configured to open the water supply valve and to supply the water to the outer tank and the washing tank up to the set water level; during the water supply, the controller is configured to control the circulation pump to circulate the washing water, which is supplied along with detergent, from the ejection port to the outer tank through the circulation route; when the controller checks that the water supply amount reaches the set water level, the controller closes the water supply valve; then, the washing machine enters a low-speed stirring process of rotating the washing tank at low speed at which the clothes are not clung to an inner wall of the washing tank; at this point, the controller is configured to control the circulation pump, whereby the washing water into which the detergent sufficiently blends, is circulated in the washing tank from the ejection port through the circulation route; when the contamination value detected by the contamination sensor is equal to or higher than a predetermined value, the controller determines that the contamination is saturated; then, the controller controls the driving unit to transfer to a high-speed rotation process of rotating the washing tank at high speed at which the clothes are clung to the inner wall of the washing tank. a washing tank that rotates while accommodating clothes; an outer tank that mounts the washing tank; a water intake port which is connected to a lowermost portion of the outer tank, wherein a circulation route is communicated with the water intake port and a circulation pump is provided in the circulation route; a driving unit that drives the washing tank wherein the washing water taken from the water intake port is ejected to the washing tank from an ejection port through the circulation route; a water supply valve that is configured to sequentially fill the outer tank and the washing tank with water; a contamination sensor that senses contamination of washing water in the outer tank; and a controller that controls the driving unit by determining a degree of the contamination based on an output of the contamination sensor, characterized in that when the clothes are put in the washing machine, the controller is configured to sense an amount of the clothes; then, the controller is configured to set a water level based on the amount of the clothes; then, the controller is configured to open the water supply valve and to supply the water to the outer tank and the washing tank up to the set water level; during the water supply, the controller is configured to control the circulation pump to circulate the washing water, which is supplied along with detergent, from the ejection port to the outer tank through the circulation route; when the controller checks that the water supply amount reaches the set water level, the controller closes the water supply valve; then, the washing machine enters a low-speed stirring process of rotating the washing tank at low speed at which the clothes are not clung to an inner wall of the washing tank; at this point, the controller is configured to control the circulation pump, whereby the washing water into which the detergent sufficiently blends, is circulated in the washing tank from the ejection port through the circulation route; when the contamination value detected by the contamination sensor is equal to or higher than a predetermined value, the controller determines that the contamination is saturated; then, the controller controls the driving unit to transfer to a high-speed rotation process of rotating the washing tank at high speed at which the clothes are clung to the inner wall of the washing tank.