Under the experimental conditions of varying the thickness(2L cm) of ginseng disc and the bulk, concentration $(C_b.{;}%)$, the experimental results were well coincided with those of the model which was set up by using the inter disc diffusion with constant diffusivity. It was therefore convinced that the extraction rate is controlled by the diffusion rate of ginseng components through the disc. The relationship between the diffusivity$(D{;}cm^2/min)$ and the mean concentration (C %) of soluble ginseng components in the disc is as follows, $ln{frac{C-C_{b0}}{C_i-C_{b0}}}=ln{frac{8}{{pi}^2}-{frac{{pi}^2D}{4L^2}{ heta}$ where $C_i(%)$ is the initial concentration of soluble ginseng components and $ heta$ (min.) is the extraction time.