Provided are a plant management system and a plant management method, which do not entail a substantial workload, cost, construction period, or installation space enable a system to be easily constructed, altered and expanded have a small maintenance load enable processing systems to be distributed and arranged in geographically separate locations and in locations where connecting the processing systems is not easy and are capable of preventing the occurrence of large-scale problems. A plant management system 100 has: a plurality of processing systems 140, 150 and memory tags 112, 122, wherein processing systems 140, 150 include reader-writers 142, 152, 153 and processing devices 141, 151, and, by writing plant management data into the memory tag 112 by means of the reader-writer 142 and then reading the plant management data by the reader-writer 152 of the processing system 150, the plant management data is transferred between the processing systems 140, 150.
