Plant facilities management system and plant facilities management system control method

The purpose of the present invention is to efficiently manage plant facilities. Equipment (2) in a plant is maintained so that equipment information (D1) related to the equipment can be read. A facility information management device (7) generates facility information by acquiring equipment information from each piece of equipment, and stores the facility information to a facility information database (T1). A facility diagnosis device (5) acquires operation data relating to each piece of equipment from a plant control unit that controls a plurality of pieces of equipment, and detects whether there is prescribed change on the basis of the difference between the operation data and statistical data recorded to an abnormality statistics database (T2). If the existence of a prescribed change is detected, a facility management device (6) associates and analyzes the operation data and facility information, and presents the analysis results to a manager (M).