This study has been initiated from observation of changes in color from samples in foaming process using batch process. The brightly whitened color of foamed plastic sample in batch process has been artfully reproduced by adjusting foaming ratio. And we measured reflectivity per wavelength using spectrophotometer in the range of visible ray at an interval of 10nm. We also measured hue (color), chroma (color purity or saturation), and value (lightness or brightness) in accordance with Musell HV/C standard, through which the relation between foaming ratio and charactics in changes in color has been analyzed. Then we further discussed regarding the cause, focus area and application of our research.