The present invention relates to a broadband wireless access system, and more particularly, to a method for efficiently determining power for ranging performed by a terminal on a target base station or a target region during handover or during changing of a region. A method for controlling uplink power for network reentry of a terminal from a first region to a second region in a broadband wireless access system, according to an embodiment of the present invention, comprises the steps of: receiving a media access control (MAC) management message including a power control parameter that is to be applied to the second region from the first region; and performing ranging to the second region by applying the power control parameter.