The dyeability of the cotton fabric with Brassica campestris extract was investigated. The colorant was extracted with methanol. Cotton fabrics were dyed at various conditions such as temperatures, concentrations, dyed times, and mordanting methods. The maximum wavelength of extract was 421nm. The highest K/S value was showed at 200% dye concentration at $60^{circ}C$, 45 minutes. As the effect of dyed temperature and mordanting on dyeability was not great, the Brassica campestris was one-color dyestuff.