Construction of a valve-member monitoring system using wireless communication is facilitated. The valve-member monitoring system is structured with operating-condition sensors each attached to each of multiple steam traps installed on a manifold. The manifold serves as a discharged condensate collecting pipe in which condensate is discharged through the multiple steam traps. The valve-member monitoring system further includes a sensor controlling terminal device that is attached to the manifold or in the vicinity of the manifold and exchanges information by radio with a central control apparatus. In the valve-member monitoring system, the terminal device is connected to the operating-condition sensors each attached to each of the steam traps installed on the manifold with lead lines. This reduces time and effort required to determine which operating-condition sensors are to be connected to the terminal device, and therefore facilitates the construction of the valve-member monitoring system, which are excellent results.