1. A spoken dialogue interface apparatus including a processor having computing device-executable instructions, the apparatus comprising: a speech recognition module, controlled by the processor, for recognizing a human's speech from a sound signal; a user intention interpretation module, controlled by the processor, for extracting a sentence from the recognized speech and interpreting a user's intention based on the sentence; a user intention selection module, controlled by the processor, for determining user intention using the interpreted user's intention and selecting a first predetermined domain action frame from a plurality of domain action frames stored in a domain action frame module; and a system response generation module, controlled by the processor, for generation a system response sentence corresponding to the determined user intention and the selected first domain action frame; wherein the first domain action frame includes service information which the user requests, and parameter information which is used to perform a service, and the first domain action frame is one of the plurality of domain action frames represented as a node in a hierarchical tree structure, and wherein, when a corresponding system response sentence does not exist in the first domain action frame due to missing of some parameter information with respect to the first domain action frame, the system response generation module generates a response using a back-off response model storage module, the system response sentence being generated with reference to a second domain action frame which exists in a service provided by a predetermined domain and is represented as a node in an upper layer of the hierarchical tree structure.