A drive current corresponding to a digital-data voltage or an analog-data voltage transmitted via a data line can be transmitted to an organic EL element of a pixel circuit provided corresponding to the intersection of a scan line and the data line. The digital-data voltage can be transmitted to the pixel circuit so as to control gray scale by digital-gray-scale modulation for decreasing power consumption. Further, the analog-data voltage can be transmitted to the pixel circuit so as to control the gray scale by analog-gray-scale modulation for increasing the display quality.