A signal processing circuit, including: first and second operational amplifiers, each configured to perform offset adjustment and being selectable to operate as an amplifier circuit to output an output voltage; a comparator circuit comparing the output voltage and a predetermined voltage; and a control circuit that, upon completion of the offset adjustment of the first operational amplifier, causes the first operational amplifier to process an input signal, while causing the second operational amplifier to stop processing the input signal and perform the offset adjustment in response to a signal of a period, and upon completion of the offset adjustment of the second operational amplifier, causes the second operational amplifier to process the input signal, while causing the first operational amplifier to stop processing the input signal and to perform the offset adjustment in response to the signal of the period, each based on a comparison result of the comparator circuit.