A signal transmission circuit includes first and second power source wirings, and a plurality of differential circuits connected in series between the first and second power source wirings. A signal transmission system includes a plurality of pairs of signal wirings, an output circuit supplying a differential signal to each of the pairs of signal wirings, and an input circuit receiving the differential signals via the pairs of signal wirings, wherein the output circuit includes first and second power source wirings, and a plurality of differential output circuits connected in series between the first and second power source wirings, and the input circuit includes a plurality of differential input circuits respectively corresponding to the differential output circuits.