1. A speech recognition device comprising speech models modeled so that the possibility that specified speech is included in input speech is output as an occurrence probability based on a given speech parameter, and said occurrence probability increases when a specified speech parameter is given, extracting said speech parameter from input speech, and recognizing speech based on the extracted speech parameter and said speech models, characterized in that said device comprises speech model spreading storage means for spreading said speech models, a plurality of speech model groups each having grouped a plurality of speech models different in said specified speech parameter are constructed, and a speech model network specifying a predetermined link relationship for the speech model groups is constructed, and a speech model group having a link relationship with a plurality of speech model groups in said speech model network is defined as a primary speech model group, and a speech model group having a link relationship with said primary speech model group in said speech model network is defined as a secondary speech model group, and when speech is recognized, unspecified speech recognizing speech models modeled so that said occurrence probability increases when a speech parameter representing speech other than specified speech capable of being recognized by speech models belonging to said primary speech model group is given, and speech models belonging to said primary speech model group are spread in said speech model spreading storage means, and a speech parameter extracted from input speech is given to speech models in said speech model spreading storage means, and speech models belonging to any of said secondary speech model groups are spread in said speech model spreading storage means based on an occurrence probability output from speech models belonging to said primary speech model group and an occurrence probability output from said unspecified speech recognizing speech models.