Abstract: A signal transmission device 10 is constructed in such a way that transmitting equipment 11 and receiving equipment 12 are connected to each other via a transmission path which consists of at least hot and cold signal lines, and a signal output stage of the transmitting equipment 11 is comprised of a current output circuit 112 and a load impedance Z (113) for converting a current I0 created by the current output circuit 112 into a voltage, the load impedance Z (113) has an end connected to the hot signal line (H) of the transmission path 13 and another end connected to the cold signal line (C) of the transmission path, and the cold signal line (C) of the transmission path is connected to a ground terminal (GNDB) of the receiving equipment 12.