A maintenance expert system having a function of data logging for a Coriolis flowmeter, the Coriolis flowmeter comprising: a CPU circuit for logging the state of the flowmeter, for monitoring/logging the internal temperature, for measuring the operation time period of the flowmeter, for detecting and recording a power abnormality caused by an instantaneous power failure occurring immediately after the power-on, with the CPU circuit comprising: a CPU comprising a plurality of internal timer counters (9A, 9B, 9C) and having a function of receiving inputs of signals from various sensors which detect a state of Coriolis flowmeter and calculating a measured value of a Coriolis force generated in a flow tube based on detection values of the various sensors; and the maintenance expert system further comprising: a power supply circuit for activating or stopping the Coriolis flowmeter; a display unit for displaying detection input data, which is input from the various sensors to the CPU, and the measured value of the Coriolis force generated in a flow tube, which is calculated by the CPU; and the display unit for displaying an indication that the flowmeter is in a warm-up period a real-time clock IC connected to the CPU via a bus line, for measuring time; a rewritable non-volatile memory EEPROM connected to the CPU via a bus line, for storing data to be input to the CPU; and a non-volatile semiconductor memory FeRAM which utilizes ferroelectric hysteresis to associate positive and negative spontaneous polarizations with "1" and "0" and which is connected to the CPU via a bus line, for storing input values from the various sensors via the CPU, and storing a calculation result obtained through a calculation performed by the CPU based on the input values from the various sensors. a detector for detecting a Coriolis force generated in a flow tube and sending the detection data to the CPU circuit, an input/output circuit for inputting data detected by the various sensors to the CPU circuit; wherein the power supply circuit is connected to the CPU circuit and drives the detector and the input/output circuit. a CPU circuit for logging the state of the flowmeter, for monitoring/logging the internal temperature, for measuring the operation time period of the flowmeter, for detecting and recording a power abnormality caused by an instantaneous power failure occurring immediately after the power-on, with the CPU circuit comprising: a CPU comprising a plurality of internal timer counters (9A, 9B, 9C) and having a function of receiving inputs of signals from various sensors which detect a state of Coriolis flowmeter and calculating a measured value of a Coriolis force generated in a flow tube based on detection values of the various sensors; and the maintenance expert system further comprising: a power supply circuit for activating or stopping the Coriolis flowmeter; a display unit for displaying detection input data, which is input from the various sensors to the CPU, and the measured value of the Coriolis force generated in a flow tube, which is calculated by the CPU; and the display unit for displaying an indication that the flowmeter is in a warm-up period a real-time clock IC connected to the CPU via a bus line, for measuring time; a rewritable non-volatile memory EEPROM connected to the CPU via a bus line, for storing data to be input to the CPU; and a non-volatile semiconductor memory FeRAM which utilizes ferroelectric hysteresis to associate positive and negative spontaneous polarizations with "1" and "0" and which is connected to the CPU via a bus line, for storing input values from the various sensors via the CPU, and storing a calculation result obtained through a calculation performed by the CPU based on the input values from the various sensors. a detector for detecting a Coriolis force generated in a flow tube and sending the detection data to the CPU circuit, an input/output circuit for inputting data detected by the various sensors to the CPU circuit; wherein the power supply circuit is connected to the CPU circuit and drives the detector and the input/output circuit. a power supply circuit for activating or stopping the Coriolis flowmeter; a display unit for displaying detection input data, which is input from the various sensors to the CPU, and the measured value of the Coriolis force generated in a flow tube, which is calculated by the CPU; and the display unit for displaying an indication that the flowmeter is in a warm-up period a real-time clock IC connected to the CPU via a bus line, for measuring time; a rewritable non-volatile memory EEPROM connected to the CPU via a bus line, for storing data to be input to the CPU; and a non-volatile semiconductor memory FeRAM which utilizes ferroelectric hysteresis to associate positive and negative spontaneous polarizations with "1" and "0" and which is connected to the CPU via a bus line, for storing input values from the various sensors via the CPU, and storing a calculation result obtained through a calculation performed by the CPU based on the input values from the various sensors. a detector for detecting a Coriolis force generated in a flow tube and sending the detection data to the CPU circuit, an input/output circuit for inputting data detected by the various sensors to the CPU circuit; wherein the power supply circuit is connected to the CPU circuit and drives the detector and the input/output circuit.