The present invention provides a semiconductor device and its driving method in which amplitude of a data line is decreased to reduce power consumption. In a reset period, a reset transistor and a switch transistor are turned on. In the reset period, an input of a potential from the reset transistor is dominant in a node D, and a selection transistor is turned off when a potential of the node D gets higher than a gate potential of the selection transistor. Thus, even though a potential of the data line changes, a potential of the node G does not change. Since the potential of the data line is not directly written in a gate of a driver transistor, it is possible to separately set an on/off potential to be applied to the gate of the driver transistor and the amplitude of the data line.