Mefenamic acid has been widely used as clinical drug for anti-inflammatory and analgesic. This drug was known to non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen and indomethacin. Although the drugs which comprise this group are of diverse chemical structures, they all share the antipyretic, analgesic and anti-inflammatory actions which are characteristic of aspirin. Action of this drugs is caused by inhibitory effect of biosynthesis of prostaglandin that are synthesized from arachidonic acid via the endoperoxide biosynthesis pathway, the initial step of which is catalysed by cyclooxygenase. Mefenamic acid has more potent inhibitory action of prostaglandin biosynthesis than aspirin. Therefore, mefenamic acid is expected to have anticoagulant activity as aspirin-like drugs. This study was carried out to investigate the sinthesis of mefenamic acid derivatives from mefenamic acid and aromatic compound of antioxidant and its antioxidative and anticoagulant activities. Synthesis of mefenamic acid derivatives was conformed by conjugation as using esterification method. Biological activities was examined using effect of anticoagulant on bleeding time and effect of antioxidant by TBA method. As a result, SJ-202 showed strong antioxidative activity and anticoagulant activity among tested 4 compounds and exhibited similar activity to aspirin at anticoagulant activity.