13. An apparatus for generating a text sentence in a target language different in a source language, based on one or more words in the source language input as keywords, the apparatus comprising: input apparatus for inputting one or more keywords in the source language without inputting a full text sentence in the source language, the one or more keywords being a segment of the full text sentence in the source language; a parallel corpus database including partial correspondence information indicating correspondence between a word/phrase in the source language and a word/phrase in the target language in each sentence pair; a sentence pair extraction means for extracting one or more sentence pairs each including more than one of the keywords from the parallel corpus database; a keyword-related phrase storage means for detecting a target-language keyword-related phrase corresponding to each source-language keyword-related phrase from the partial correspondence information of each sentence pair and storing the detected target-language keyword-related phrase in the form of a keyword-related phrase table; a text candidate generation means that performs dependency relationships of each keyword-related phrases in the source language and in the target language of the pair of keyword-related phrases described in the keyword-related phrase table and generates one or more target-language sentence candidates by using a target language keyword-related phrase generation model and a language model by assuming dependency relationships or two or more pairs of keyword-related phrases; and an output means for outputting at least one text sentence candidate corresponding to the full text sentence in the source language.
18. An apparatus according to claim 13 , wherein the text candidate generation means assumes dependency relationships among keyword-related phrases in the target language described in the keyword-related phrase table and generates one or more target-language text sentence candidates, the apparatus further comprising source-language text candidate generation means that assumes dependency relationships among keyword-related phrases in the source language described in the keyword-related phrase table and generates one or more source-language text candidate, and wherein at least one set of text sentences in the source and target languages is output from the output means.