Abstract: This research aims at developing a redesign problem solver which proposes suitable modifications of a given artifact for a new requirement or an inconvenience. We concentrate on the two issues, capturing design rationales of the given artifact and organizing general redesign strategies. For the former issue, we propose an ontology of functional concepts, which enables the redesign system to identify functional structures representing a part of design rationales automatically. It particularly includes a new category of functional concepts called meta-functions for representation of dependency among functions of components. For the latter issue, we describe an ontology of the redesign strategies. Some general strategies for proposing redesign solutions in terms of the concepts in the ontology are shown. It reveals conceptualization behind the redesign strategies and then helps us specialize the Soar architecture into a universal redesign engine.