Antioxidant and anti-rheumatoid activities of Cirsium japonicum leaf extract (CJLE) were investigated in this study. CJLE had similar DPPH radical scavenging activity and reducing power to ascorbic acid and several flavonoids. Rheumatoid arthritis (RA) is a chronic inflammatory tissue-destructive disease, partly related with functions of hyaluronidases (HAases) and collgenases. CJLE ($1,000;{mu}g/mL$) had approximately 60.7 and 31.9% inhibition of HAase and collagenase activity, respectively. Also, CJLE inhibited lipopolysaccharide (LPS)-induced nitrite production in a dose-dependent manner, and CJLE ($1,000;{mu}g/mL$) suppressed approximately 70% of LPS-induced nitrite production effectively in RAW 264.7 macrophage cells. CJLE had inhibitory effects on the adherence of monocytic THP-1 to human umbilical vein endothelial cell (HUVEC) monolayers to the basal level. Inhibitory effect of CJLE on the adhesion was caused by suppression of tumor necrosis factor-a-upregulated expression of vascular cellular adhesion molecule-1 (VCAM-1) and E-selectin. We expect that CJLE may alleviate the inflammatory process in rheumatoid synovium, and these findings will raise the possibility of the usage of C. japonicum as a traditional pharmaceutical of anti-rheumatoid arthritis.