PURPOSE: To drastically simplify an operation by designating the maximum and minimum frequencies of bands and setting the center frequencies and Q of respective bands.

CONSTITUTION: An audio signal from an audio unit 10 is transmitted to an amplifier 11 through a graphic equalizer 9. CPU 1 controls the graphic equalizer 9 through an input/output port 8. CPU 1 inputs the band change command of a user, the maximum frequency FL and the minimum frequency fH from a keyboard 4 and a detector 5 through the input/output port 8. CPU 1 is provided with ROM 2, and ROM 2 stores a program calculating fk and Qk for the respective bands based on fL and fH. The signal of the type of a source selected in the audio unit 10 is inputted from a source detector 6 to CPU 1 through the input/output port 8, and Fo and Q are set in accordance with the selected source.