To provide a control/supervisory signal transmission system in which simple communication control can be performed without any control unit, and a wiring-enabled distance is longer than that of a conventional system.

The control/supervisory signal transmission system is comprised of: a plurality of slave stations provided correspondingly to a plurality of working devices and connected by a common data signal line; and a mediation station connected to the data signal line. The data signal line is comprised of a plurality of independent sequences centralized to the mediation station. The plurality of working devices are divided into one or a plurality of sets each including at least two devices, and the working devices belonging to the same set with different sequences of the data signal line connecting them are determined to have correspondence. The mediation station extracts supervisory data from a supervisory signal transmitted from a sensor unit via the slave stations and sends the supervisory data as control data to the other working device having correspondence to the working device including the sensor unit that has sent the supervisory data.