A voice recognition unit recognizes a recognition word code corresponding to a speech uttered by a user along with a command code for executing a function of a control object. A function execution unit executes a function corresponding to the command code from the voice recognition unit. A message outputting unit extracts a recognition word corresponding to the recognition word code from a recognition word storing unit, and generates a message properly utilizing the extracted recognition word. The generated message is notified to the user via a display or a speaker, so that the user can confirm that the uttered speech is adequately recognized.