This work aims at a contrastive investigation of the tense and aspect in Japanese and English, placing emphasis on formal solutions of problems which are applicable to machine translation, based on Head-Driven Phrase Structure Grammar and Discourse Representation Theory. After formulating DRS's for Japanese predicates with and without "te iru," it addresses the issue of how to resolve the ambiguity in terms of the aspectual meanings in "te iru"-marked sentences. Then the problem of Consecutio Temporum (sequence of tense) is discussed on the basis of a four-layered syntactic hierarchy. Lastly, the result of an implementation of the rules proposed in the preceding part of the work is exhibited.