The present invention is directed to suppress dullness of a scanning signal in a scanning signal line drive circuit. A bistable circuit is provided with an input terminal (43) for receiving a first clock signal (CK), an input terminal (48) for receiving a control signal (CT), an input terminal (49) for receiving a level down signal (LD), an output terminal (51), a thin film transistor (T2), and a thin film transistor (TA). The thin film transistor (T2) has a gate terminal connected to a first node (N1), a drain terminal connected to the input terminal (43), and a source terminal connected to the output terminal (51). The thin film transistor (TA) has a gate terminal connected to the input terminal (48), a drain terminal connected to the first node (N1), and a source terminal connected to the input terminal (49). The potential of the control signal (CT) becomes the high level in a control period as a period except for the first one horizontal scanning period in a vertical blanking period. The level down signal (LD) is a potential lower than DC power supply potential (Vss).