The present invention relates to a wireless access system, and more particularly, to a method for saving power of a femto base station. The present invention includes obtaining reference synchronization information used in a prescribed area to enable a first femto base station to perform a sleep mode operation, shifting to a sleep mode if a mobile station does not exist within the first femto base station, and enabling the first femto base station to be synchronized with at least one second femto base station belonging to the prescribed area using the reference synchronization information, wherein each of the femto base stations included in the prescribed area achieves synchronization of the sleep mode operation using the reference synchronization information. Accordingly, it is able to minimize power consumption of a femto base station and interference with a macro cell in a wireless access system supporting a femtocell. And, a mobile station within a femtocell is able to perform reliable communications.