A washing machine, having a water tub and a rotary drum to receive laundry, to perform washing using bubbles, the washing machine comprising: a water supply unit to supply wash water; a detergent supply unit to store detergent and a water supply pipe to supply wash water to the detergent supply unit; a water replenishment pipe diverging from the water supply pipe to replenish wash water; a bubble generation unit to generate bubbles; and a control unit to control the water supply unit to directly supply the wash water into the water tub before bubble generation, to control the rotary drum to rotate at a predetermined RPM based on determining that wash water contained in the water tub reaches to a predetermined water level, to control the water supply unit to supply the wash water and the detergent based on determining that a predetermined time has elapsed since the rotary drum rotates, and to control the bubble generation unit to generate bubbles from the supplied wash water, and to perform the washing using the generated bubbles; wherein the water supply unit supplies the wash water to the detergent supply unit such that the detergent stored in the detergent supply unit is dissolved to form concentrated detergent liquid; wherein the water supply unit directly supplies the wash water into the water tub not through the detergent supply unit but through the water replenishment pipe; and wherein the control unit controls the water supply unit to directly supply the wash water into the water tub through the water replenishment pipe to wet the laundry before the wash water and the detergent are supplied into the space between the water tub and the rotary drum. a water supply unit to supply wash water; a detergent supply unit to store detergent and a water supply pipe to supply wash water to the detergent supply unit; a water replenishment pipe diverging from the water supply pipe to replenish wash water; a bubble generation unit to generate bubbles; and a control unit to control the water supply unit to directly supply the wash water into the water tub before bubble generation, to control the rotary drum to rotate at a predetermined RPM based on determining that wash water contained in the water tub reaches to a predetermined water level, to control the water supply unit to supply the wash water and the detergent based on determining that a predetermined time has elapsed since the rotary drum rotates, and to control the bubble generation unit to generate bubbles from the supplied wash water, and to perform the washing using the generated bubbles; wherein the water supply unit supplies the wash water to the detergent supply unit such that the detergent stored in the detergent supply unit is dissolved to form concentrated detergent liquid; wherein the water supply unit directly supplies the wash water into the water tub not through the detergent supply unit but through the water replenishment pipe; and wherein the control unit controls the water supply unit to directly supply the wash water into the water tub through the water replenishment pipe to wet the laundry before the wash water and the detergent are supplied into the space between the water tub and the rotary drum.