An output transistor (2) has a source connected to a VDD1 and a drain connected to an output terminal (1). A pre-driver (3) receives a signal varying in accordance with a data input signal (DIN), and provides a gate signal (SG1) to a gate of the output transistor (2), the gate signal (SG1) transiting between the VDD1 and a potential (VP) at a power source end (4). When a VDD2 is output from an output node (N1) and an assist signal (SA) makes a first transition corresponding to the transition of the gate signal (SG1) from HIGH to LOW, the drive assist circuit (20) performs an assist operation in which a potential of the output node (N1) is temporarily brought down from VDD2.