The present invention relates to a laundry machine and to a method for controlling same. The method for controlling a laundry machine comprising two or more balancing units which are movable independently of each other, comprises: a sensing step of sensing the weight of the laundry to be washed, while maintaining a substantially same phase difference between the balancing units and rotating a drum; and an eccentricity-reducing step of reducing the eccentricity of the drum while rotating the drum and simultaneously moving at least one of the balancing units.