This paper reports on the semantics study regarding the words expressing ‘Space’ in Japanese. The previous studies on Japanese spatial nouns were focused on individual meanings of the vocabulary. The present study, however, sought to categorize each space to each spatial noun in order to sort spatial nouns more systematically. It was found that unlike region-reference spatial nouns, direction-reference spatial nouns could be used in both exterior region-reference and partial region-reference. Partial region-reference is classified with boundary region-reference and interior region-reference. Furthermore, in order to make theoretical frame for translating of nouns which have various meanings, we analyzed the characteristics of sentence structure of Japanese spatial noun /mae/, and proposed “ambiguity analysis rules of spatial noun /mae/. This rule is proposed under the hypothesis that the meaning of /mae/ is determined by the meaning of predicate and the property of reference. This rule also contributes to a job of translation related to ambiguities of spatial-nouns.