PURPOSE: To correctly and properly execute a translation even in the case the same character-string which is not an idiom appears in a sentence by determining whether a certain word is regarded as an idiom or not by referring to the conditions before and behind its word.

CONSTITUTION: The device is constituted of an inference engine 1, a rule 2 and a dictionary 3. The inference engine 1 reads in an input sentence 4, executes an analysis, while referring to the dictionary 3, based on support shown by the rule 2, and outputs an analytic result 5. The rule 2 consists of a fundamental rule 2-1 and an idiom processing rule 2-2. The idiom processing rule 2-2 checks how to stand in a line of the previous and the next words described in a certain word in the dictionary 3 (that is, designation to be interpreted as an idiom, when what kind of word comes to an arbitrary position before and behind its word being a center word of the idiom), and how to stand in a line of the word in an actual input sentence, and in the case the word in the input sentence appears by how to stand in a line as designated in the dictionary 3, a series of word groups thereof are interpreted as an idiom.