It is an object to provide a transmissive liquid crystal display device in which power consumption is reduced and deterioration in display quality is suppressed. As a backlight, a surface-emission light source is employed. The light source is a light source which performs surface light emission, so that the light emission area is large. Accordingly, the backlight can effectively radiate heat. Thus, even in the case where an image signal is not input to a pixel for a long period, the pixel can hold the image signal. In other words, both a reduction in power consumption and a suppression of deterioration in display quality can be realized.