To enable the accurate system performance tuning in a short time by pigenholing a system environment and the database state and then deciding a tuning point and a parameter based on the fuzzy inference.

A state data collection means 11 collects a general system environment 13 and the state of a data base 14 of the system performance tuning. The collected state data are pigenholded and stored in a log file 15 via a log function 12. An evaluation report production means 21 outputs a tuning hint report 22 based on the data stored in the file 15 and the specialist knowledge and in consideration of the system characteristic and scale. A tuning point inference means 31 infers the stored state data based on the specialist knowledge and via the fuzzy inference considering the system characteristic and scale, etc., and outputs a tuning point parameter 32. In such a constitution, a person in charge can accurately perform a tuning job.