A dishwasher comprising a tub which defines a dishwashing space; a sump in which the wash water sprayed into the tub is collected; a spraying arm (5, 9) comprising first and second channels (531, 532) configured to circulate wash water distinguishably and a plurality of spraying holes configured to spray the wash water supplied to the first channel in one direction such that the spraying arm (5,9) is rotated in a clockwise direction, and a plurality of other spraying holes configured to spray the wash water supplied to the second channel in another direction such that the spraying arm (5, 9) is rotated in a counter-clockwise direction, wherein the entire cross section area of the spraying holes corresponding to the first channel is different from the entire cross section area of the spraying holes corresponding to the second channel; a supply pump comprising an impeller and a motor configured to drive the impeller and configured to supply the wash water collected in the sump to the spraying arm; a flow path conversion unit configured to selectively supply wash water to the first channel or the second channel according to the drive of the supply pump; and a controller implemented to control the drive of the motor, wherein the controller controls the drive of the motor to alternatively supply wash water to the first and second channels (531, 532) by the operation of the flow path conversion unit, wherein the controller distinguishes a first state in which the wash water is supplied to the first channel and a second state in which the wash water is supplied to the second channel from each other, based on a difference between a first current value flowing to the motor in the first state and a second current value flowing to the motor in the second state, wherein the spraying holes corresponding to the first channel are configured to spray wash water toward the dishwashing objects held in the tub, characterised in that the spraying holes corresponding to the second channel comprise a first spraying hole (5121, 9121) configured to spray wash water toward a dispenser configured to accommodate dishwasher detergents and a second spraying hole configured to spray wash water toward a filter provided in an upper surface of the sump, and wherein when the dishwasher is driven according to a preset dishwashing course, the controller preferably controls the supply pump to supply wash water via the second channel for a preset time period after determining the current value flowing to the motor when wash water is supplied to the first channel and the current value flowing to the motor when wash water is supplied to the second channel. a tub which defines a dishwashing space; a sump in which the wash water sprayed into the tub is collected; a spraying arm (5, 9) comprising first and second channels (531, 532) configured to circulate wash water distinguishably and a plurality of spraying holes configured to spray the wash water supplied to the first channel in one direction such that the spraying arm (5,9) is rotated in a clockwise direction, and a plurality of other spraying holes configured to spray the wash water supplied to the second channel in another direction such that the spraying arm (5, 9) is rotated in a counter-clockwise direction, wherein the entire cross section area of the spraying holes corresponding to the first channel is different from the entire cross section area of the spraying holes corresponding to the second channel; a supply pump comprising an impeller and a motor configured to drive the impeller and configured to supply the wash water collected in the sump to the spraying arm; a flow path conversion unit configured to selectively supply wash water to the first channel or the second channel according to the drive of the supply pump; and a controller implemented to control the drive of the motor, wherein the controller controls the drive of the motor to alternatively supply wash water to the first and second channels (531, 532) by the operation of the flow path conversion unit, wherein the controller distinguishes a first state in which the wash water is supplied to the first channel and a second state in which the wash water is supplied to the second channel from each other, based on a difference between a first current value flowing to the motor in the first state and a second current value flowing to the motor in the second state, wherein the spraying holes corresponding to the first channel are configured to spray wash water toward the dishwashing objects held in the tub, characterised in that the spraying holes corresponding to the second channel comprise a first spraying hole (5121, 9121) configured to spray wash water toward a dispenser configured to accommodate dishwasher detergents and a second spraying hole configured to spray wash water toward a filter provided in an upper surface of the sump, and wherein when the dishwasher is driven according to a preset dishwashing course, the controller preferably controls the supply pump to supply wash water via the second channel for a preset time period after determining the current value flowing to the motor when wash water is supplied to the first channel and the current value flowing to the motor when wash water is supplied to the second channel.