1. A voice recognition apparatus for recognizing voice uttered by an operator, comprising: a portion for performing a voice recognition process on a voice signal corresponding to said voice to thereby acquire vocal phrase data indicating the uttered phrase; a portion for detecting a point of time when said operator has started uttering said voice and a point of time when said operator has ended uttering said voice on the basis of a signal level of said voice signal to thereby generate first utterance duration information; a portion for capturing a mouth of said operator to acquire mouth image data; a portion for detecting a point of time when said operator has started uttering said voice and a point of time when said operator has ended uttering said voice on the basis of said mouth image data to thereby generate second utterance duration information; and an output portion for outputting said vocal phrase data as long as said first utterance duration information is approximate to said second utterance duration information.