To provide a natural language analysis system and a natural language analysis method, capable of improving the accuracy of interpreting meaning and contents of an analysis object sentence regardless of a field of the analysis object sentence and a configuration of the sentence itself.

A natural language analysis system stores a semantic concept dictionary storing various content words and function words, one or more semantic tags are attached to each of the content words, and a part of respective semantic tags associates the content word with a word or the like appearing in the same sentence as the content word or another sentence to have a cause-effect relationship with the content word. The system analyzes the analysis object sentence with reference to the semantic concept dictionary, attaches a semantic tag showing a cause-effect relationship to the analysis object sentence, and outputs the analysis object sentence. Therefore, a client computer side can presume a context of a sentence composed of a plurality of passages astride the passages.