The purpose of this study is to scientifically proof possibility of development of natural dye which has antimicrobial activity with Chelidonium majus var. asiaticum. For that silk fabrics dyed with Chelidonium majus var. asiaticum extracts were tested for anti-microbial activity. Bacterials used for test of anti-microbial activity were Staphylococcus aureus ATCC 6538, Klebsiella pneumoniae ATCC 4352 and Trichophyton mentagrophytes IFO 5466. The results of experiment were as follows ; 1. The more the number of times of dyeing increase the more value of K/S increased. 2. Reduction of bacterium against Staphylococcus aureus ATCC 6538 of silk fabrics dyed with Chelidonium majus var. asiaticum extracts was 99.9% without reference to the number of times of dyeing. 3. Reduction of bacterium against Staphylococcus aureus ATCC 6538 of silk fabrics dyed with Chelidonium majus var. asiaticum extracts was 99.9% after irradiation of 20 hour without reference to the number of times of dyeing. 4. Reduction of bacterium against Staphylococcus aureus ATCC 6538 of silk fabrics dyed with Chelidonium majus var. asiaticum extracts was over 94.8% after dry cleaning. As above silk fabrics dyed with Chelidonium majus var. asiaticum extracts were acquired a high anti-microbial activity against Staphylococcus aureus ATCC 6538.