The present invention relates to a method and device for encoding or decoding an object audio signal or rendering the object audio signal in a three-dimensional space. The method for processing an audio signal, according to one aspect of the present invention, comprises the steps of: generating a first object signal group and a second object signal group obtained by classifying a plurality of object signals according to a determined method; generating a first down-mix signal for the first object signal group; generating a second down-mix signal for the second object signal group; generating first object extraction information in correspondence with the first down-mix signal with respect to object signals included in the first object signal group; and generating second object extraction information in correspondence with the second down-mix signal with respect to object signals included in the second object signal group.