For a display device having a solar cell and a power buffer for keeping stored electric power, a display system which has a low-power drive mode, self-contained power and no need for recharging or power wiring is provided. The display system includes a solar cell using a thin-film semiconductor, a power storage element for temporarily storing the produced power, a driving circuit, a matrix display unit, a display rewrite instruction unit for inputting screen rewrite and a control circuit and starts rewriting a display when power sufficient to rewrite an image screen is stored in the solar cell. The display device having remarkable portability and no limited battery life, which controls a display mode depending on the power produced by the solar cell, can display even when power generation is low and allows self-contained power even if the storage element has a small capacity, can be obtained.