A dishwasher comprising: a tub for providing a cleaning space; a first rack positioned in the tub for receiving cleaning objects therein and a second rack provided under the first rack; a spray arm positioned under the second rack for spraying cleaning water; a tower nozzle fastened to the second rack for spraying the cleaning water toward the first rack; and a tower connector including an arm securing body provided to pass through the spray arm, and a tower attachable/detachable body provided to be projected from the arm securing body to supply the cleaning water to the tower nozzle when the cleaning water is introduced to the arm securing body, characterized by further comprising: a spray arm supporter including a supporter body (71, 73 and 75) for supporting the spray arm and having the arm securing body to be fastened thereto, a chamber in the supporter body for introducing the cleaning water thereto, an arm supply hole in the chamber for supplying the cleaning water to the spray arm, and a tower supply hole in the chamber for supplying the cleaning water to the arm securing body; and a flow passage change over unit provided in the chamber for opening either the arm supply hole or the tower supply hole depending on a pressure of the cleaning water in the chamber, wherein the flow passage change over unit is provided to be able to reciprocate and rotate for moving toward the arm supply hole and the tower connector if the cleaning water is supplied to the chamber, and moving toward a direction of introduction of the cleaning water if the cleaning water is not supplied to the chamber. a tub for providing a cleaning space; a first rack positioned in the tub for receiving cleaning objects therein and a second rack provided under the first rack; a spray arm positioned under the second rack for spraying cleaning water; a tower nozzle fastened to the second rack for spraying the cleaning water toward the first rack; and a tower connector including an arm securing body provided to pass through the spray arm, and a tower attachable/detachable body provided to be projected from the arm securing body to supply the cleaning water to the tower nozzle when the cleaning water is introduced to the arm securing body, characterized by further comprising: a spray arm supporter including a supporter body (71, 73 and 75) for supporting the spray arm and having the arm securing body to be fastened thereto, a chamber in the supporter body for introducing the cleaning water thereto, an arm supply hole in the chamber for supplying the cleaning water to the spray arm, and a tower supply hole in the chamber for supplying the cleaning water to the arm securing body; and a flow passage change over unit provided in the chamber for opening either the arm supply hole or the tower supply hole depending on a pressure of the cleaning water in the chamber, wherein the flow passage change over unit is provided to be able to reciprocate and rotate for moving toward the arm supply hole and the tower connector if the cleaning water is supplied to the chamber, and moving toward a direction of introduction of the cleaning water if the cleaning water is not supplied to the chamber. a spray arm supporter including a supporter body (71, 73 and 75) for supporting the spray arm and having the arm securing body to be fastened thereto, a chamber in the supporter body for introducing the cleaning water thereto, an arm supply hole in the chamber for supplying the cleaning water to the spray arm, and a tower supply hole in the chamber for supplying the cleaning water to the arm securing body; and a flow passage change over unit provided in the chamber for opening either the arm supply hole or the tower supply hole depending on a pressure of the cleaning water in the chamber, wherein the flow passage change over unit is provided to be able to reciprocate and rotate for moving toward the arm supply hole and the tower connector if the cleaning water is supplied to the chamber, and moving toward a direction of introduction of the cleaning water if the cleaning water is not supplied to the chamber.