An acoustic material has been newly developed from the viewpoint of environmental protection. Since, we used a natural resource, bamboo fiber, to manufacture sound absorbing material. The normal incidence sound absorption coefficient of bamboo fiber material was measured at the influences of thickness, air space depth, apparent density and the bamboo fiber size using an impedance tube. In addition, the characteristic impedance and the propagation constant of the materials were measured. The contour lines of the sound absorption coefficient by calculation were pictured as the thickness and the air space depth of material respectively density. We tried to find the best combination of samples of different densities for the improvement of sound absorption effects with the whole weight of the material constant. The sound absorption coefficient effect can be improved by combination felt, board and air space depth. Consequently, fundamental design criteria have been confirmed using the newly developed bamboo fiber material for sound.