Robot systems have recently been studied for real-world situations such as space exploration, under water inspection, and disaster response. In extreme environments, a robot system has a probability of fault. Therefore, considering fault tolerance is important for success of missions. In prior research, we proposed a distributed cooperative fault diagnosis method for internal components of robot system. This method consists of some diagnosis devices called diagnosers' which observe the state of a electrical component. Some diagnosers execute the diagnosis independently and in parallel, and we assume that they are connected using wireless communication. In this paper, we propose a technique which involves gathering the diagnosis results. Further we confirmed that this method can detect the faults of components in simplified fault situations by conducting computer simulations.