A display system in which the luminance of light-emitting elements in a light-emitting device is adjusted based on information on an environment. A sensor obtains information on an environment as an electrical signal. A CPU converts, based on comparison data set in advance, the information signal into a correction signal for correcting the luminance of EL elements. Upon receiving this correction signal, a voltage changer applies a predetermined corrected potential to the EL elements. Thus, this display system enables control of the luminance of the EL elements.