A unit circuit that constitutes a shift register includes a gate output lowering transistor (T01) whose source terminal is supplied with a second gate low voltage (Vgl2) and a gate output reset transistor (T03) Whose source terminal is supplied with a first gate low voltage (Vgl1), as constituent elements associated with the lowering of gate output. At the time of lowering the gate output, the gate output lowering transistor (T01) is made to be in an on state, and thereafter the gate output reset transistor (T03) is made to be in the on state. In this case, the gate terminal of the gate output reset transistor (T03) is supplied with a scanning signal or a signal having a waveform equivalent to that of the scanning signal outputted from the unit circuit in a subsequent stage.