The diverse techniques for condition monitoring of the test material have been applied in the material test loop (System Safety Benchmark Facility: SSBF) simulating the water condition that of the boiling water reactor. In this paper, two methods of condition monitoring are mainly described. One is a thinning process monitoring of material wall by using pulse echo methods with ultrasonic sensors. The other is early detection of a leakage by measuring and analyzing the SSBF parameter and the temperature and humidity in the protector. Although the experiment is still going on, the validity of the proposed methods of condition monitoring has been confirmed.