In rheumatoid arthritis (RA), epigenetic alterations are observed in synovial cells. However, epigenetic regulatory mechanisms are largely unknown. Therefore, we identified epigenetic regulator(s) contributing RA pathogenesis in vivo by microarray gene expression and qPCR analyses using mRNA obtained from whole ankle tissues of experimental arthritis and control mice. As a result, epigenetic regulator Uhrf1 (Ubiquitin Like With PHD And Ring Finger Domains 1) mRNA was significantly increased in arthritis tissue. We also explored UHRF1 mRNA expression was significantly increased in RA patients’ synovium compared with Normal and Osteoarthritis by reanalysis of RNA-seq data sets registered in GEO. In addition, immunohistochemical analysis in mice model clarified that Uhrf1 was localized in both synovial fibroblasts (SF) and macrophages in hyperplastic synovium. To analyze the physiological functions of Uhrf1 in synovial tissues, we generated and analyzed SF- (fcKO) and macrophage- (mcKO) specific Uhrf1 conditional knockout (cKO) mice. After arthritis induction, clinical and histological examinations showed that significant severe phenotypes were observed only in fcKO mice, but not in mcKO, when compared with respective littermate control (Cont). Finally, to reveal molecular functions of Uhrf1 in RA pathogenesis, we performed RNA-seq using primary SF obtained from fcKO and Cont mice. 171 genes were up-regulated more than 2 fold in fcKO-SF compared with Cont-SF (p<0.05). KEGG pathway analysis on 171 genes showed that top 2 enriched pathways were “rheumatoid arthritis” and “Cytokine-cytokine receptor interaction”, which were contained 12 genes. We validated expression changes of 12 genes in human RA-SF by qPCR. As the result, UHRF1 knockdown significantly accelerated CCL20 mRNA expression in RA-SF. These results indicated that UHRF1 in SF may play a role in negative feedback mechanisms in RA pathogenesis and cytokine-related gene expressions may be regulated by UHRF1 in RA synovial fibroblasts.