Power consumption of a display device is reduced. The display quality of the display device is improved. Video with high display quality is displayed regardless of the usage environment. The display device includes a first pixel performing display with reflected light, a second pixel including a light source and performing display with light from the light source, a driver portion driving the first pixel and the second pixel, a photometric portion measuring and outputting illuminance of the external light, and a control portion generating a first gray level output to the first pixel and a second gray level output to the second pixel on the basis of information of the illuminance input from the photometric portion and outputting the first and second gray levels to the driver portion. In addition, the control portion generates the first and second gray levels so that the first gray level is the largest among the combinations of the first and second gray levels at which chromaticity and luminance of light obtained by adding light output from the first pixel and light output from the second pixel have predetermined values.