In this paper, we present a superordinate and subordinate relationship computation method. We have proposed a vector space search method for computing causal relationships. We extend this method to compute directionality relationships of superordinate and subordinate concepts. By using general knowledge expression with a tree structure, we generate vector spaces for computing those directionality relationships. This method dealing with the combination of those directionality relationships makes it possible to realize a superordinate and subordinate relationship computation, according to various objectives related to directionality relationships. We have implemented a superordinate and subordinate relationship computing system for directionality relationships among technical terms in the aerospace engineering .eld. We clarify the effectiveness and feasibility of our system by several experiments.