A hands-free telephone apparatus which supports a user so as not to restrict the functions of the hands-free telephone processor. The hands-free telephone processor inquires the state of the mobile telephone when the model of the connected mobile telephone is unknown. If the hands-free telephone processor receives the notification of the state of the mobile telephone in response to this inquiry, the hands-free telephone processor refers to the warning information stored in advance. The hands-free telephone processor determines whether the mobile telephone is in a state of restricting the functions of the hands-free telephone apparatus available to the user. If it is necessary to output a warning, the hands-free telephone processor outputs the warning message registered corresponding to the state of the mobile telephone in the warning information. The hands-free telephone processor issues a restart command to the mobile telephone to restart the mobile telephone.