In a liquid crystal display device capable of displaying a moving image and a still image, a reduction in contrast due to light scattering in a reflective pixel portion or the like is suppressed and consumed power is reduced. As a driving method of a transflective liquid crystal display device including a plurality of pixels each including a plurality of light-transmitting pixel portions and a reflective pixel portion, an image signal for color display is supplied to the plurality of light-transmitting pixel portions and a signal for black display is supplied to the reflective pixel portion in a moving-image display period, and an image signal of black-and-white grayscale is supplied to the plurality of light-transmitting pixel portions and the reflective pixel portion in a still-image display period.