In this research, redundant mechanism for RTC-CANopen Manager is investigated to improve reliability of the system built with RTC-CANopen. In the RTC-CANopen system, it becomes impossible to monitor the CANopen devices when RTC-CANopen Manager is down. RTC-CANopen Manager, it has frameworks both of RT-Middleware and CANopen and converts the interface for another subsystems. Thus, the robot constructed by using RTC-CANopen can't work correctly during RTC-CANopen Manager is down. We investigated that doubling RTC-CANopen Manager has effect for that problem, and tested the way to monitor. By solving the problem, the reliability of RTC-CANopen will be improved. And, it becomes a key to spread RT-Middleware.