When instruction data is received, a prescribed service is performed on the basis of the received instruction data. A processing result of the service is sent to a service processing apparatus as an instruction data transmission source. If the processing result of the service is normal, the instruction data is copied. One instruction data is sent to a service processing apparatus that is to performing a next service on the basis of a description in the instruction data, and the other instruction data is stored. If it is judged that an abnormality has occurred in the service processing apparatus as the instruction data transmission destination, the stored instruction data is sent to a service processing apparatus capable of performing a substitute service for the next service.