MicroRNAs (miRNA) play a key role for morphogenesis or various diseases like cancer. Small RNA, has no protein-encoding sequence, has been indentified to interfere with stability or translational ratio of mRNA. MiRNA is one of the small RNA family and has been analyzed about the synthesis, function and target genes. These researches lead exploitation of new nucleic drugs. Many researches have been reported for relationship between miRNA and rheumatoid arthritis (RA)/osteoarthritis (OA). MiR-146a and -155 were mainly reported for RA, miR-140 was mainly reported for OA including cartilage development. This article was summarized various analysis for miRNA with RA and OA.