To provide a machine translation device for making it unnecessary for a user to operate a correcting work when the similar original sentence reappears by allowing the user to correct only the original sentence.

This machine transaction device is provided with an inputting part 1 for allowing a user to execute the input of an original sentence, translation instruction, and the pre-edition of translation, translation information storing part 2 for storing translation being the translated result of the original sentence and analytic information and generation information in the transition state of translation, word and rule dictionary part 3 for storing vocabulary information related with words and grammar information for operating translation, translation executing part 4 for translating the original sentence stored in the translation information storing part by using the word and rule dictionary part 3, difference extracting and registering part 5 for extracting difference information between the analytical information and generation information of the translated result stored in the translation information storing part and the analytical information and generation information of the re-translated result when the user executes the edition and re-translation of the original sentence by the inputting part 1, and for registering the extracted difference information in the word and rule dictionary part 3, display part 6 for displaying the translated result, and control part 7 for operating the whole operation control.