In response to an operation such as power-on or power-off, channel change and sound volume change, a television set combined with a personal computer automatically makes e-mail with information in a predetermined format indicative of the operation attached. The e-mail is automatically sent to another television set to inform the other television set of operation of the own television set. On the other hand, the e-mail can be sent to a rating company for audience share survey. The television set automatically reads the received e-mail and attachment to change the indication of display. The television set has storage of the received information for analysis of an abnormality. Abnormality can be also sensed through abnormal act on the remote controller apt to be taken by a person in panic or off the truck. The television set refuses information from unknown address for blocking an attack of a stranger.