A dishwasher comprising: a tub having a space for accommodating an object to the washed; a sump provided at a lower part of the tub for storing wash water; and a pair of main arms provided in the sump for spraying wash water received from the sump to the object, a pair of auxiliary arms (140, 150) for spraying wash water to the object, mounted on the main arms, characterized in that said pair of auxiliary arms (140, 150) extend in a direction which forms a predetermined angle with respect to the main arms and in that said pair of auxiliary arms (140, 150) is rotatable about an axis defined by a direction in which the auxiliary arms extend; and in that the dishwasher further comprises a power transfer assembly for transferring rotary forces of the main arms to the auxiliary arms (140, 150), wherein the power transfer assembly comprises: a fixed gear unit (200, 1200, 2200, 3200) fixed to the sump; a rotary gear unit (500, 1500, 2500, 3500) rotatably mounted on the main arms so as to be rotated while being engaged with the fixed gear unit (200, 1200, 2200, 3200) by rotation of the main arms; and a link member (600, 1600, 2600) connected to the rotary gear unit (500, 1500, 2500, 3500) and the auxiliary arms (140, 150), the link member (600, 1600, 2600) being configured to be reciprocated by rotation of the rotary gear unit (500, 1500, 2500, 3500), wherein a rotation shaft of the rotary gear unit is formed at one of the main arms. a tub having a space for accommodating an object to the washed; a sump provided at a lower part of the tub for storing wash water; and a pair of main arms provided in the sump for spraying wash water received from the sump to the object, a pair of auxiliary arms (140, 150) for spraying wash water to the object, mounted on the main arms, characterized in that said pair of auxiliary arms (140, 150) extend in a direction which forms a predetermined angle with respect to the main arms and in that said pair of auxiliary arms (140, 150) is rotatable about an axis defined by a direction in which the auxiliary arms extend; and in that the dishwasher further comprises a power transfer assembly for transferring rotary forces of the main arms to the auxiliary arms (140, 150), wherein the power transfer assembly comprises: a fixed gear unit (200, 1200, 2200, 3200) fixed to the sump; a rotary gear unit (500, 1500, 2500, 3500) rotatably mounted on the main arms so as to be rotated while being engaged with the fixed gear unit (200, 1200, 2200, 3200) by rotation of the main arms; and a link member (600, 1600, 2600) connected to the rotary gear unit (500, 1500, 2500, 3500) and the auxiliary arms (140, 150), the link member (600, 1600, 2600) being configured to be reciprocated by rotation of the rotary gear unit (500, 1500, 2500, 3500), wherein a rotation shaft of the rotary gear unit is formed at one of the main arms. a fixed gear unit (200, 1200, 2200, 3200) fixed to the sump; a rotary gear unit (500, 1500, 2500, 3500) rotatably mounted on the main arms so as to be rotated while being engaged with the fixed gear unit (200, 1200, 2200, 3200) by rotation of the main arms; and a link member (600, 1600, 2600) connected to the rotary gear unit (500, 1500, 2500, 3500) and the auxiliary arms (140, 150), the link member (600, 1600, 2600) being configured to be reciprocated by rotation of the rotary gear unit (500, 1500, 2500, 3500), wherein a rotation shaft of the rotary gear unit is formed at one of the main arms.