2. The voice recognition apparatus according to claim 1 , further comprising: an input unit inputting a plurality of voice signals with respect to a plurality of reject word candidates relating to a recognition word to which a reject word is added, to the extraction unit; wherein the extraction unit is designed to extract a feature amount from each of the inputted voice signals; wherein the collation unit calculates the degree of similarity between the voice signal and each of the recognition words stored in the word dictionary by using the feature amount extracted by the extraction unit, and is designed to output the result of recognition based upon the calculated degree of similarity; and the reject word generation unit calculates the number of voice signals each corresponding to a recognition word to which the reject word is added as the result of recognition for each of the reject word candidates based upon the result of recognition outputted by the collation unit, and stores a reject word candidate having a large number of calculations carried out by the reject word generation unit as a reject word relating to the recognition word to which the reject word is added.
4. The voice recognition apparatus according to claim 2 , wherein the reject word generation unit is designed to store one portion of the reject word candidate in the word dictionary as a reject word relating to the recognition word to which the reject word is added.