The level of a storage capacitor line changes between two types, an H level and an L level. As a result of this change, the voltage applied to a liquid crystal is shifted so that a sufficient voltage is applied to the liquid crystal to perform a display operation. Then, by changing the voltage value of the difference between a first level and a second level, the contrast and screen brightness are adjusted. Furthermore, the capacitances generated at the locations where the two storage capacitor lines and the data line intersect are set to be substantially the same.