A speech recognition apparatus includes a first storing unit configured to store a first acoustic model invariable regardless of speaker and environment, a second storing unit configured to store a classification model that has shared parameters and non-shared parameters with the first acoustic model to classify second acoustic models, a recognizing unit configured to calculate a first likelihood with regard to the input speech by applying the first acoustic model to the input speech and obtain calculation result on the shared parameter and a plurality of candidate words that have relatively large values as the first likelihood, and a calculating unit configured to calculate a second likelihood for each of the groups with regard to the input speech by use of the calculation result on the shared parameters and the non-shared parameters of the classification model.