PURPOSE: To facilitate the adjustment by allowing a manufacturer to store a reference data being the result of correcting an IC to be controlled into an optimum video image state and allowing the user to adjust the circuit only within a prescribed range based on the reference data thereby eliminating the need for an external circuit for the correction.

CONSTITUTION: When a control signal given from a remote controller is discriminated to be the 1st control signal by a discrimination means 7, a 1st output means 8 outputs a digital data corresponding to the signal to a conversion means 12. The means 12 converts the data into a DC control voltage to control an IC 13 to be controlled. Then the circuit is adjusted to the optimized video image state and the result is stored in a storage means 9 as a reference data. When the means 7 discriminates the control signal as a 2nd control signal by the user, a 2nd output means 10 gives an output it to the means 12 only when the data is within a prescribed range around the reference data stored in the means 9. Thus, no external circuit for correction is required to facilitate the adjustment.