Driving method of display device and display device

It is an object to reduce power consumption of a display device which can perform multi-gray scale display and to suppress deterioration of an element included in the display device. The usage of a display device includes a first initialization period in which the gray scale level of an entire pixel portion is converted into a first gray scale level and a second initialization period in which the gray scale level of an entire pixel portion is converted into a second gray scale level. In the first initialization period, scanning of a plurality of signals and weighting of a holding period of each signal are performed. Therefore, the small number of scanning of signals can realize voltage application for an appropriate time with respect to each of a plurality of gray scale storage display elements included in the display device.