1. A method of performing translations between first and second natural languages comprising: a first step of sectioning a source text described by a first natural language word by word and storing the words in storage; a second step of deriving information regarding the parts-of-speech of the stored source words through retrieval of the parts-of-speech information from a lexical dictionary storage in which words are registered together with information regarding the parts-of-speech thereof; a third step of deriving target words in the second natural language which are equivalent in meaning to the respective stored source words in the first natural language; a fourth step of translating a first pattern of a string of parts-of-speech formed by gathering the parts-of-speech for each of the stored source words derived in said second step into a pattern in which the order of the parts-of-speech is in accordance with said first natural language, into a second pattern of a string-of-parts of speech with an order in accordance with said second natural language by referring to a translation pattern table which registers therein the correspondences between first patterns of parts-of-speech strings defining sequences of parts-of-speech of the first natural language and second patterns of parts-of-speech strings defining sequences of parts-of-speech of the second natural language; and a fifth step of generating a sentence in the second natural language by sequencing said target words in accordance with the sequential order of the parts-of-speech in said translated second pattern of the string of parts-of-speech of said second natural language.