Provided is a differential amplifier circuit with a small circuit size. When a differential voltage (Vinp−Vinn) is higher than a predetermined voltage, a PMOS transistor (4) is turned ON. At this time, a current source (12) is connected in parallel to a current source (11), and the current source (12) supplies a drive current to a differential amplifier circuit (10). In other words, the current sources (11 and 12), rather than only the current source (11), supply a total current (I11+I12) to the differential amplifier circuit (10) as the drive current. Accordingly, a slew rate of an output voltage (Vout) is increased. Two PMOS transistors and the current source (12) are simply required for controlling the slew rate of the output voltage (Vout), and hence the differential amplifier circuit (10) is small in circuit size.