To inform a user of contents of an image or the cause of a non-display state, when an image cannot be displayed in a display device.

A display device 100 using a cholesteric liquid crystal requires a relatively large electric power that is consumed upon displaying an image. Even when the display device 100 cannot display an image, however, if transmission of the image is possible, the device transmits signals to a cell phone 200 and makes it display the image. If transmission of the image cannot be effected, the device transmits an image representing little remaining quantity of power to the cell phone 200, to display on the cell phone 200 so as to inform a user of the cause of the non-display state. When the device cannot display an image caused by the temperature in a display unit 102, the device transmits an image that represents the temperature to the cell phone 200 being high and informs a user of the cause of the non-display state.