PURPOSE: To eliminate the need for a mixing circuit and a BPF for display and to display the signal intensity of each band securely by providing every amplification block with an amplifier which amplifies or attenuates only a band component set to each band-pass filter, and cascading those respective amplification blocks.

CONSTITUTION: Plural amplification blocks 26a∼26e are cascaded between a signal input terminal 27 and a signal output terminal 28 and provided with BPFs 9a∼9e and amplifiers 10a∼10e which amplify or attenuate only band components set by the BPFs 9a∼9e. Difference signals of subtracting circuits of those blocks 26a∼26e are applied to a multiplexer 32 to select and input band signals to a converting circuit 20 automatically and successively. Pieces of switching information on operation keys 16a and 16b are latched by latch circuits 14a∼14e through a shift register 30 and pieces of switching information C0∼C4 are applied to the blocks 26a∼26e and circuit 20 through a multiplexer 31. Thus, the need for a mixing circuit and a display BPF is eliminated and the signal intensity values of respective bands are displayed on display devices 8a∼ 8e by the output of the circuit 20.