Provided a circuit board including an input terminal to which a high-frequency signal is input, a high-frequency amplifier for amplifying the high-frequency signal input to the input terminal, at least one distributor distributing the high-frequency signal, a plurality of high-frequency processing circuits of which transmission path lengths for inputting each of the high-frequency signals distributed by the distributor into signal inputting sections of the plurality of high-frequency processing circuits are different from one another, and a plurality of attenuating devices which are mounted at previous stages of each of the plurality of high-frequency processing circuits and possess amounts of attenuation which increase with decrease of the transmission path lengths.