PURPOSE: To attain accurate preventing maintenance by identifying and selecting whether it is data required for analysis from environment information in generated log data.

CONSTITUTION: In respective user systems 10, hardware information and environment information are collected whenever a log phenomenon occurs and log data is written in a log file 11. A remote maintenance center system 20 stores log data transferred from respective user systems 10 in a log file 21 and they are taken out and analyzed. Consequently, the remote maintenance center system 20 can take out only log data operating the system which is effective for analysis to attain analysis when environment data in log data is identified. Thus the state of the system can accurately be analyzed.