Disclosed is a method for reducing vibration during dehydration of a washing machine having a ball balancer provided to a spin basket for accommodating clothes. The disclosed method for reducing vibration comprises: a test rotation step for rotating the spin basket at a measurement rotation count, which is lower than a resonance rotation count and at which the balls of the ball balancer move in a circle; a vibration period measurement step for measuring a vibration period of the spin basket, the vibration period being caused by the eccentric distribution of the clothes in the test rotation step; and an acceleration start timing acquisition step for acquiring acceleration start timing on the basis of the vibration period such that the balls and the eccentrically distributed clothes are arranged to face each other in opposite phases during resonance, when the rotation count of the spin basket passes the resonance rotation count if there is acceleration at a preset determined acceleration speed from the measurem
