Provided is a plant equipment state gathering system which simplifies the work relating to attaching and/or replacing a detection device that detects the state of plant equipment. A plant equipment state gathering system is provided with a detection device, a mobile terminal, a network construction device and a data storage device. The detection device includes a tag unit that can store, in a non-contact manner, at least some setting information that at least includes network information for connecting to the network from the mobile terminal. The mobile terminal includes a tag control unit that allows the tag unit of the detection device to automatically store, in a non-contact manner, at least some of the setting information. When network information is stored in the tag unit of the detection device by the mobile terminal the network construction device uses this network information to determine whether to allow the connection of the detection device to the network.