Provided is a voice recognition system capable of, while suppressing negative influences from sound not to be recognized, correctly estimating utterance sections that are to be recognized. A voice segmenting means calculates voice feature values, and segments voice sections or non-voice sections by comparing the voice feature values with a threshold value. Then, the voice segmenting means determines, to be first voice sections, those segmented sections or sections obtained by adding a margin to the front and rear of each of those segmented sections. On the basis of voice and non-voice likelihoods, a search means determines, to be second voice sections, sections to which voice recognition is to be applied. A parameter updating means updates the threshold value and the margin. The voice segmenting means determines the first voice sections by using the one of the threshold value and the margin which has been updated by the parameter updating means.