A lot of horizontal shaft type ventilation fan systems were installed and have been continuously operated in the Rokkasho reprocessing plant. The maintenance method by TBM (Time Based Maintenance) and periodical vibration diagnosis has been applied for the stable operation to keep containment function of the facilities. Although creep phenomenon of bearings in a fan and a motor is one of the important factors to evaluate its integrity, it is not easy to recognize the creep earlier from the monitor data of vibration trend. In order to solve this problem, authors have evaluated "the acoustic test data and frequency analysis of acceleration parameters". Based upon these experience, we designed a flowchart to judge the integrity of bearings easily and applies them as the first step to Rokkasho reprocessing plant. Furthermore in the near future we plan to apply this method for other continuous operated equipments such as liquid pumps and motors.