An improvement support system including an input unit, a display, an arithmetic processing unit and a storage unit, the storage unit stores analytical data containing analytical information corresponding to "phenomenon" or "influence" and "cause" or "measures" for each of failure modes, and malfunction generation historical data in which malfunction information formed based on the contents of malfunction and related to the failure mode of the analytical information is sequentially accumulated every time the malfunction is detected after the system is started. The arithmetic processing unit has a function of retrieving the analytical data using the malfunction information as a key and detecting the failure mode correlated with the malfunction. Thus, the number of malfunctions related to the analytical information regarding each failure mode is counted and the total number of malfunctions related to the failure mode is displayed with the contents of the failure mode in the display.