A washing machine is provided. The washing machine controls a dehydration rotation speed by detecting a phase difference between a ball balancer and the laundry. Further, the washing machine controls a dehydration rotation speed at a dehydration segment based on a dehydration rotation speed of a driving device. Thereby, the washing machine minimizes energy using in a dehydration process by accelerating the dehydration rotation speed at a point at which a phase difference between the ball balancer and the laundry is a maximum. Further, by accelerating the dehydration rotation speed at a point at which the phase difference is a maximum, a vibration of the washing machine is remarkably reduced.