1. An interactive processing apparatus comprising: a user goal extracting unit for referring to a user goal knowledge composed of user goals for defining intentions of input statements in natural language entered by a user, in order to extract a user goal from each input statement, thereby generating a semantic representation of the input statement; an interaction history storage unit for storing semantic representations of user goals and input statements output by the user goal extracting unit, as well as semantic representations output by a next action determining unit to be defined later; a system goal determining unit for determining a system goal corresponding to a given user goal from a system goal knowledge composed of system goals constituting action goals of a system; a goal frame generating unit for retrieving from an action sequence knowledge a system action sequence knowledge node corresponding to a system goal which is input either from the system goal determining unit or from an action feasibility judging unit to be defined later, the sequence knowledge being composed of system action sequence knowledge nodes needed to achieve system goals, the goal frame generating unit further generating a goal frame pairing the system goal with the corresponding system action sequence knowledge node; a goal frame storage unit for storing goal frames output by the goal frame generating unit; an action feasibility judging unit for retrieving a semantic representation from the interaction history storage unit in order to set arguments for, and judge feasibility of, the action in a goal frame being held by the goal frame storage unit; the action feasibility judging unit outputting an action command if the action is judged to be feasible; the action feasibility judging unit generating a new system goal if the action is not judged to be feasible, the newly generated system goal being output to the goal frame generating unit; an external application driven upon receipt of an action command from the action feasibility judging unit, the external application further outputting a result of execution of the action; and a next action determining unit for determining, in response to the result of action execution output by the external application, the action to be executed next in the action sequence of a goal frame being held by the goal frame storage unit, the next action determining unit further outputting to the interaction history storage unit a semantic representation acquired from the result of the action execution.