Background : Osteoarthritis is an inflammatory disorder related with oxidative stress and apoptosis leading to cartilage damage. Recently, Cirsium japonicum var. maackii (CJM) was reported to play a protective role in various inflammatory response. However, the role of CJM in cartilage degeneration and osteoarthritis progression is still unknown. Therefore, this study aims to investigate the protective effect of CJM in a animal model of osteoarthritis and cartilage degradation. Methods and Results : First, in order to determine active ingredient contents of CJM, we were carried out total polyphenolic content and total flavonoid content analyses. As a result, dried aerial parts of CJM were found to contain 149.2 ± 24.1 ㎎·GAE/g dry weight and 27.9 ± 2.0 ㎎·NE/g dry weight in boiling water extraction. Also, the HPLC analysis of CJM showed major compounds identified as cirsimarin and cirsimaritin. In addition, CJM protected against osteoarthritic cartilage destruction in an osteoarthritis mouse model induced by destabilization of the medial meniscus, as demonstrated by histopathological analysis. Conclusion : The results of this study demonstrate that CJM may protect against the osteoarthritis and cartilage destruction. Further study is needed to identify the mechanism for their improvement effects of osteoarthritis and cartilage destruction.