This dissertation is concerned with the relationship between morphological tense forms of Japanese, such as (r)u ("non-past") and ta ("past"), and their temporal interpretation. The goal of the research reported here is to establish a simple overall theory. The analysis focuses on the following sentence types: simple sentences, complex sentences (without conditional sentences), conditional complex sentences and sentences with an embedded clause. We will show here a few examples of problems as to temporal interpretations. In simple sentences, there are cases such as (1), which deviate from the norm of "normal" interpretation. Sentence (1) (with the “past” form of ta) can be uttered felicitously even in a situation where the bus in question has not yet arrived. (1)Busu ga ki-ta! Bus nom come-ta ‘The bus is coming.’ Or ‘The bus has come.’ In complex sentences, the antecedent clause in sentences with toki 'when', can take either (r)u or ta forms in sentence (2), while it cannot take the ta form in sentence 93), although the antecedent clauses in both sentences are interpreted as non-past. (2) Kondo a-u/at-ta toki, hanashi-ma-su. Next-time see-(r)u/see-ta toki talk-polite-(r)u ‘Next time when (I) see (you), (I) will tell (it to you).’ (3)Yuushoku o su-ru/*shi-ta toki, biiru o nom-u. supper acc do-(r)u/do-ta toki beer acc drink-(r)u ‘When (I) take supper, (I) will drink beer.’ In regard to conditional complex sentences, there can be a problem interpreting ta, as in hypothetical sentence (4) below. The ta of the consequent clause in example (4) cannot be evaluated (interpreted) as being the same as the ta in example (5) where we have an indicative sentence. (4) Taroo wa benkyoo shi-ta ra, shaken ni pasu shi-ta (no ni). Taro top study do-ta ra exam in pass do-ta (SFP-‘wishing’) ‘Had Taro studied, he should/would have passed the exam.’ (5) Taroo wa shiken ni pasu shi-ta. ‘Taro passed the exam.’ In this account the morphemes (r)u and ta will be associated with a single interpretation. Therefore, the difference between (2) and (3) will be attributed to two distinct modes of composition. In order to solve the problem of simple sentences wuch as (1) (which deviate from the norm of "normal interpretations"), a pragmatic (contextual) approach will be introduced. In regard to conditional sentences, interpretations will be classified on the basis of truth relations and temporal interpretations of antecedent and consequent. In order to treat the range of observed truth relations, a model of time and worlds will be introduced. In summary, in order to solve the problematic phenomena of relationships between the tense forms and their interpretations, the following approaches will be taken: (i) Use of a time model; (ii) Analysis of lexical properties; (iii) Sentence composition; (iv) Contextual analysis for pragmatic aspects.