The purpose of this study was to evaluate the antioxidant and anti-adipogenic activities of Ligularia stenocephala (L. stenocephala) extract. The contents of the total polyphenol of the extract was 55.950 mg GAE/g residue. Antioxidant activities of L. stenocephala were evaluated by free radical scavenging ability and a reducing power test. 2,2'azino-bis- (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and α-α-diphenyl-β-picrylhydrazyl (DPPH) free radical scavenging activities of the extract were approximately 90% and 70%, respectively. Reducing power of the extract was 258.833 mg TE/g residue. The anti-adipogenic activity of L. stenocephala extract was examined in 3T3-L1 cells. During adipocyte differentiation, the 3T3-L1 cells were treated both with and without the extract. L. stenocephala extract suppressed the lipid accumulation in a concentration-dependent manner in the 3T3-L1 cells. The L. stenocephala extract inhibited the expression of peroxisome proliferator activated receptor γ (PPARγ) and adipocyte protein 2 (aP2) proteins, compared with control adipocytes. These results indicate that L. stenocephala could be regarded as a potential source natural antioxidant and an anti-obesity agent.