The present invention includes specific sentence generator 14 for generating a piece of sentence data specific to an application from a grammar stored in grammar storing unit 12 and correction information stored in correction information storing unit 13 and then storing the piece of data in specific sentence storing unit 15, topic shift unit 16 for shifting a general topic stored in general topic storing unit 17 to a topic specific to an application on the basis of the piece of sentence data and then storing the topic in shifted topic storing unit 18, natural speech recognition unit 21 for recognizing speech by dictation with a shifted topic and then storing the recognition result in recognition result storing unit 22, candidate sentence generator 19 for generating candidate sentences from a grammar and then storing the sentences in candidate sentence storing unit 20, and matching unit 23 for determining a final recognition result by matching candidate sentences with a recognition result.