In an input transistor of current mirror circuit, it is intended to prevent the current generated by Early effects from appearing in the output current of the current mirror circuit. Having an Early voltage detector 22 of same connection and structure as a driver circuit 21, and connected in parallel to the driver circuit 21, the current flowing in input transistor Q9 of the Early voltage detector 22 is detected. Output current (current IQ11) of Early voltage detector 22 is added to input current (current IQ5) of driver circuit 21. As a result, in input current (current IQ7) of current mirror circuit 25, current .alpha. due to Early voltage effects can be canceled. At the same time, current .alpha. due to Early voltage effects generated in input transistor Q5 of current mirror circuit 25 is prevented from appearing in output current (current IQ8) of current mirror circuit 25.