An image storage for storing digital still image data is connected to a television set for selectively watching a broadcast program in a first mode or a still image transmitted from the image storage in a second mode. The image storage has an input circuit for receiving a control signal form the television set and an output circuit for transmitting a still image signal to the television set on the basis of the digital still image data, the output circuit being responsive to the control signal. The television set, on the other hand, has an output circuit for transmitting the control signal to the image storage. By means of the control signal, the image storage is automatically turned on or off when the television set is turned on or off, respectively. The control signal makes image storage operative or inoperative when the television set is in the second mode or in the first mode, respectively, to save power consumption with the television set in the first mode. The image storage may be further connected to a printer, wherein the image storage further has an output circuit for transmitting an output signal to the printer in response to the control signal from the television set, the output signal being an image signal to be printed or a control signal for the printer function.