PURPOSE: A speech recognition based intelligent robot system is provided to actively cope with both analyzable speech and not analyzable speech by a speech recognition technology, thereby outputting a proper response to a user. CONSTITUTION: A speech recognition unit(1) converts a speech signal inputted from a user into texts by using a speech recognition technology. A natural language DB(2) stores one or more text information for analyzing content of the speech signal. When the text information converted by the speech recognition unit is stored in the natural language DB, a control unit(3) performs an operation corresponding to the text information. When the text information converted by the speech recognition unit is not stored in the natural language DB, the control unit transmits the text information to an operator terminal connected to a network. The control unit performs an operation corresponding to received response information of the operator terminal.