Slope greening techniques are being used to reinforce cutting and embankment slopes, and spraying substrate onto slope surface has been widely practiced to protect slopes from water erosion. The mixture of bark and peat moss is commonly used as a substrate, and the substrate to which adhesive was added is sprayed onto the slope surface on which steel wire mesh is placed. Though the spraying of the substrate is aimed at preventing erosion of substrate layers, they were frequently damaged by severe erosion before vegetation grows in the substrate. To reduce the damage of substrate layers by erosion, bamboo fiber was newly produced through the mechanical crushing of raw bamboo and was applied to the substrate of slopes at several construction sites, and as a result the erosion of substrate layer was minimized at most of the sites. In the present study erosion tests were conducted using box-type miniature slopes to assess resistance to erosion of the substrates including the bamboo fiber and bark, and also the effects of steel wire mesh placement and adhesive addition on erosion. The bamboo fiber was far more effective than the bark for preventing erosion in case steel wire mesh was not placed; the amount of erosion for the bamboo fiber was only 5 % of that for the bark. By installing steel wire mesh the amount of erosion increased 20- and 3-fold for the bamboo fiber and bark, respectively. Addition of adhesive to the bark enhanced the amount of erosion 3-fold. The permeability of the bamboo fiber was three times as high as that of the bark. The greater resistance to erosion for the bamboo fiber than for the bark was ascribed to the bamboo fiber's characteristics such as entangled association, and lesser fine fraction percentage, higher permeability, and greater tensile strength than the bark.