The purpose of this study was to investigate the antibacterial effects of natural colors extracted from yellow natural dyes(Tumeric, Amur Cork Tree and Onion Shell). The water and the methanol extracts of Tumeric and Amur Cork Tree significally decreased the growth of E. coli in vitro and the methanol extract of Tumeric exhibited the strongest inhibitory effect among the samples. Silk and nylon fabrics dyed with water and methanol extracts of the yellow natural dyes showed antimicrobial activities against E. coli and Staph aureus in the Bioassay Test. Nylon fabric dyed with methanol extracts of them showed strong antibacterial effect on E. coli compared with that of water extracts. However, slik fabrics dyed with the extracts could not reduce the growth of E. coli. Silk or nylon fabrics dyed with methanol or water extracts of yellow natural dyes showed antimicrobial activities against Staph aureus. The antimicrobial activity of the fabrics dyed with methanol extracts from Tumeric, Amur Cork Tree and Onion Shell was stronger than that of water extracts, especially, the fabrics dyed with Tumeric extract showed the highest antibacterial property among the dyed fabrics.