A washing machine comprising: a casing having an entry hole on a front surface thereof; a tub disposed in the casing and configured to contain water, the tub having an entrance hole on a front surface thereof; a drum rotatably provided in the tub; a gasket connecting the entry hole of the casing and the entrance hole of the tub; at least one nozzle installed in the gasket and configured to spray water into the drum; a washing motor configured to rotate the drum; a circulation pump having a circulation pump motor and being configured to pump water discharged from the tub to the at least one nozzle; and a processor configured to: alternatively repeat acceleration and deceleration of the washing motor such that the washing motor is accelerated to make laundry in the drum rotate along with the drum while stuck to the drum owing to a centrifugal force, and the washing motor is decelerated to make the laundry separated from the drum; and operate the circulation pump motor to spray water through the at least one nozzle, wherein the circulation pump motor is accelerated and decelerated, characterized in that the acceleration and deceleration of the circulation pump motor is performed in response to the acceleration of the washing motor and the braking of the washing motor, respectively, and wherein the circulation pump motor is a variable speed motor whose rotation speed is controllable, and the respective acceleration and deceleration of the circulation pump motor is performed with a certain gradient. a casing having an entry hole on a front surface thereof; a tub disposed in the casing and configured to contain water, the tub having an entrance hole on a front surface thereof; a drum rotatably provided in the tub; a gasket connecting the entry hole of the casing and the entrance hole of the tub; at least one nozzle installed in the gasket and configured to spray water into the drum; a washing motor configured to rotate the drum; a circulation pump having a circulation pump motor and being configured to pump water discharged from the tub to the at least one nozzle; and a processor configured to: alternatively repeat acceleration and deceleration of the washing motor such that the washing motor is accelerated to make laundry in the drum rotate along with the drum while stuck to the drum owing to a centrifugal force, and the washing motor is decelerated to make the laundry separated from the drum; and operate the circulation pump motor to spray water through the at least one nozzle, wherein the circulation pump motor is accelerated and decelerated, characterized in that the acceleration and deceleration of the circulation pump motor is performed in response to the acceleration of the washing motor and the braking of the washing motor, respectively, and wherein the circulation pump motor is a variable speed motor whose rotation speed is controllable, and the respective acceleration and deceleration of the circulation pump motor is performed with a certain gradient. alternatively repeat acceleration and deceleration of the washing motor such that the washing motor is accelerated to make laundry in the drum rotate along with the drum while stuck to the drum owing to a centrifugal force, and the washing motor is decelerated to make the laundry separated from the drum; and operate the circulation pump motor to spray water through the at least one nozzle, wherein the circulation pump motor is accelerated and decelerated, characterized in that the acceleration and deceleration of the circulation pump motor is performed in response to the acceleration of the washing motor and the braking of the washing motor, respectively, and wherein the circulation pump motor is a variable speed motor whose rotation speed is controllable, and the respective acceleration and deceleration of the circulation pump motor is performed with a certain gradient.