This experiment was to find out the exact amount of iron component in filature water affecting or the coloring and iron component content in the raw silk after the quantitative analysis of iron component in the filature water, cocoon bave and raw silk. 1. In Korea the extent of iron component in filature water is 0.01-0.77 PPM, and the average amount is 0.23 PPM. 2. The sample water from wells contains more than twice as much iron component as the river water. 3. The iron component content in the cocoon bave (Fe$_2$O$_3$ 0.0096%) and that in the raw silk (Fe$_2$O$_3$ 0.0084%) are similar. But it should be noticed that while the ash content in cocoon bave is twice as much as raw silk, the same amount of ash in raw silk has twice as much iron component as the cocoon bave. 4. The amount of iron component in filature water has great effect on the resolution and absorption of iron component contained in the raw silk during cooking and reeling. That is, when the amount of iron component is small, the rate of iron component resolution from the cocoon bave increases and finally the raw silk comes to contain much less iron component than the cocoon bave, but when the iron component amount is over 0.40 PPM, the raw silk happens to contain more iron component than the cocoon bave. 5. The iron component in filature water makes the raw silk grayish and the more the iron component, the grayer the raw silk. 6. While even very small amount of iron component can affect the depth of raw silk, relatively large amount of Mn component does not have so much influence on the coloring.