A multi-stage amplifier includes first and second amplifier stages, and first and second capacitors. The first amplifier stage includes a input line having a first input end and a second input end; an input terminal block connected to the second input end; an amplifier circuit amplifying a first signal input to the first input end; an output line having a first output end where the first signal amplified is output, and a second output end; and an output terminal block connected to the second output end. The second amplifier stage includes components similar to that of the first amplifier stage. The first capacitor is connected between the first output end of the first amplifier stage and the first input end of the second amplifier stage. The second capacitor is connected to any one of the input and output terminal blocks of the first and second amplifier stages.