A transmission apparatus for differential communication includes a driver bridge circuit and a pair of noise protection circuits. The driver bridge circuit includes four output devices that are independently connected between each of a pair of transmission lines and a power line or a ground line. Each noise protection circuit is provided to a corresponding transmission lines. Each noise protection circuit includes a ground potential detector and an impedance controller. The ground potential detector detects a potential of the corresponding transmission line with respect to the ground line. The impedance controller causes an impedance of the corresponding transmission line with respect to the ground line to become equal to an impedance of the other transmission line with respect to the ground line, when the detected potential becomes outside a predetermined potential range.