The operation management and the equipment control of plants are carried out based on measurements obtained from flow meters set up in the plants. Therefore, it is necessary to always observe the flow meters to detect and diagnose a fault, and to correct measurements. However, the fault of the flow meters (bias of the indicated value) can be repaired only in regular maintenance under present circumstances. If the flow meters with bias of the indicated value can be detected beforehand, a reasonable repair plan can be planned. Moreover, it comes to be able to correct the bias of the indicated value while plant operation. In this paper, a fault diagnosis method using historical database is developed about the flow meters set up in the plant where the state of the plant always changes by influence of load variation. It aims to make the fault diagnosis system that can satisfy with the specifications required from users. The effectiveness of this method is demonstrated by using a simulation of tank-pipeline system.