Colorants were prepared by extraction of natural indigo which was harvested just in the blooming season(in the late of July). 100 g of fresh leaves soaking in 1 ιwater was kept at 3$0^{circ}C$, 30 hours. A solution of 3g/l calcium hydroxide was added into it to precipitate dye substance and it was freezing-dried into powder form. The fermentation and dyeing conditions were investigated. The results obtained are summarized as follows; K/S value of dyed silk fabrics of fermentation conditions was higher at 95$^{circ}C$ for 20 min. than at 4$0^{circ}C$ for 20 hours. Furthermore, K/S value of dyed silk fabric was raised by the addition of 5g/l of glucose and 5g/l of NaOH. K/S value of dyed silk fabric was raised by the addition of 5g/l of glucose and 5g/l of NaOH. K/S value increased as extending of dyeing time when dyed till 2 hours at 3$0^{circ}C$. K/S value decreased in order of 3$0^{circ}C$, 4$0^{circ}C$ and 5$0^{circ}C$, at the various dyeing temperatures and dyeing concentrations, and colour fastness ranged from 4 to 5 grade in terms of washing, perspiration and light fastness.