A display device in which a pixel defect is less likely to be perceived is provided. The display device includes a display portion where pixels are arranged in a matrix, and a sensor portion including a photoelectric conversion element. First, the display portion is divided into a first region and a second region. Next, first light is emitted from the pixel included in the first region, and the luminance of the first light is detected by the photoelectric conversion element. Moreover, second light is emitted from the pixel included in the second region, and the luminance of the second light is detected by the photoelectric conversion element. Then, the luminance of the first light is compared to the luminance of the second light, and on the basis of the comparison result, one of the first region and the second region is divided into a third region and a fourth region. By repeating these operations, a defective pixel is detected. Luminance represented by image data can be corrected on the basis of the detection result of the defective pixel.