One embodiment of the present invention is to prevent deterioration of display quality from occurring in a display device provided with an active matrix substrate even when a larger size or a higher resolution is employed and a drive frequency is increased. In an active matrix substrate of a liquid crystal display device, a discharge control signal line is disposed so as to be arranged along each gate line and discharge TFTs are provided for each source line in numbers equal to the number of the gate lines. The gate terminal, source terminal, and drain terminal of the discharge TFT are connected to the discharge control signal line, the storage capacitance line, and its adjacent source line, respectively. Each storage capacitance line is provided with the common potential Vcom. Each discharge control signal line is provided with a signal which turns on the discharge TFT for a predetermined period of every one horizontal period.