Artificial rocks have been often used in aquariums, zoos, botanical gardens and parks etc. However, recently, opportunity to use the artificial rocks on surfaces of various structures is increasing. This probably comes from the reason that using the artificial rocks is effective from a view point of balancing with environment, so demand of them is expected to increase in near future. To meet the demand, it is desired to clarify strength, deformability and thermal properties of artificial rocks. In this study, these properties for two types of artificial rocks at high and low temperatures and effects if thermal hysteresis on them were examined. The results indicated that the artificial rocks are able to be used on the surfaces on structures exposed to temperature change in wide variety of natural environment.