An unknown word is additionally registered in a speech recognition dictionary by utilizing a correction result, and a new pronunciation of the word that has been registered in a speech recognition dictionary is additionally registered in the speech recognition dictionary, thereby increasing the accuracy of speech recognition. The start time and finish time of each phoneme unit in speech data corresponding to each phoneme included in a phoneme sequence acquired by a phoneme sequence converting section 13 are added to the phoneme sequence. A phoneme sequence extracting section 15 extracts from the phoneme sequence a phoneme sequence portion composed of phonemes existing in a segment corresponding to the period from the start time to the finish time of the word segment of the word corrected by a word correcting section 9 and the extracted phoneme sequence portion is determined as the pronunciation of the corrected word. An additional registration section 17 combines the corrected word with the pronunciation determined by a pronunciation determining section 16 and additionally registers the combination as new word pronunciation data in the speech recognition dictionary 5 if it is determined that a word obtained after correction has not been registered in the speech recognition dictionary 5. The additional registration section 17 additionally registers the pronunciation determined by the pronunciation determining section 16 as another pronunciation of the corrected word if it is determined that the corrected word has been registered.