1. A voice recognition system comprising: a standard acoustic model having a standard vector generated according to information on voice; a first feature vector generation section for reducing noise from an input signal generated from an uttered voice corresponding to a designated text to generate a first feature vector; a second feature vector generation section for generating a second feature vector from the input signal having the noise; and a preparation section for generating an adaptive vector based on the first feature vector, the second feature vector and the standard vector, and preparing a speaker adaptive acoustic model suitable for the uttered voice.