The authors are studying on a new shower cleaning system of removing environmental pollutant materials from an exhaust gas. In this report the decomposition of the collected chemical pollutant materials by photocatalysis was experimentally investigated by using ethylamine as a sample. The chemical reactor was composed of coaxial cylinders between which the packed bed of glass beads coated by photocatalyst was formed, and "Black Light" was located on the center of the cylinders to radially emit ultraviolet rays. The dependency of the decomposition rate of ethylamine was investigated on the radial thickness of the packed bed, the diameter of the glass bead and the flow rate. It was found from the experimental results that only the most inner layer of the packed bed is effective in photocatalysis reaction due to the fact that ultraviolet rays cannot go through the packed bed and irradiate only on the most inner layer.