Provided is a shift register configured by cascade connecting unit circuits each including a bootstrap circuit. In at least one example embodiment, for the unit circuits, a time period during which a transistor is in an ON state and a clock signal is high level corresponds to a clock passing period. Among transistors whose one conduction terminal is connected to a gate of the transistor, channel lengths of transistors configured such that a low-level potential is fed to gates of the transistors to turn the transistors to an OFF state in the clock passing period and that a low-level potential is applied to the conduction terminal of the transistors in the clock passing period are made longer than the channel length of the transistor. With this, it is possible to reduce a leakage current in the clock passing period, and to prevent the fluctuation of a gate potential of the transistor and dullness in an output signal from occurring.