Disclosed are a method for processing a dialog based on processing instructing expression in a multi-modal environment and an apparatus therefor. The method for processing a dialog in an information processing device capable of processing digital signals includes the steps of: extracting an instructing expression from an inputted sentence; generating an intermediate instructing expression representing the modifying relations between the words constituting the extracted instructing expression; and searching the object corresponding with the intermediate instructing expression in a predetermined object search range. Thus, a terminal can be effectively and conveniently used without separately clarifying various instructing expressions representing things or objects with the terminal.