A redundant system includes devices communicably coupled via communication paths. Each device is communicably coupled via two or more of the communication paths to two or more of the other devices. Each device performs wired communication via the communication paths with the devices communicably coupled to the each device via the communication paths in a normal state. Each device includes a wireless communication unit. When each device communicates with the two or more of the other devices under a condition that malfunction occurs in two or more parts in the redundant system, the each device performs the wired communication via the communication path with a counterpart device with which the wired communication via the communication path is enabled, and switches from the wired communication via the communication path to wireless communication and continues communication with the counterpart device with which the wired communication via the communication path is disabled.