The anti-obesity activity of the Cucubita moschata Duch. extracts was investigated. The inhibitory effect on triglyceride accumulation was shown in 3T3-L1 preadipocyte. The lipid accumulation of the ethanol extract in 5 mg/mL concentration was shown to be 75.4%, where as that of water extract was shown to be 85.2%. The survival rate of the cell in the viability test was shown to be 86.5% in the 0.5-5 mg/mL concentration. Total polyphenol content was highest in the water extract(46.54 ± 0.02 mg). These results suggest that Cucubita moschata Duch. extracts have a potential as anti-obesity material by reducing the lipid accumulation.