A signal processing circuit is configured by connecting a plurality of basic circuits connected in series, each of the basic circuits comprising an arithmetic circuit subjecting a first input signal and a second input signal to a signal processing; a first selection circuit outputting the first input signal or an output signal of the arithmetic circuit; and a second selection circuit outputting the second input signal or an output signal of the arithmetic circuit, so as to make it possible to change operations of the circuit as a whole by properly making a selection on which signal should be output with the aid of the first and second selection circuits, and to execute different signal processing on a single circuit depending on the selection.