Batch leaching test (Japanese leaching test No.18) were performed on the forest soil and burnt sand mixed with the two types of wood ash containing toxic inorganic elements such as Cr and As. Forest soil showed higher buffer capacity than burnt sand but high ash application dose resulted in the excess of the capacity. Leached amount of electrolyte became lower in forest soil if the same doses were applied. Concentration of Cr (VI) leached from the mixture of forest soil did not exceed Japanese environmental standards relating soil contamination even though 20% of the ashes were added (ash/ash+soil or sand: wt.%, d.b.) while that from mixture of burnt sand exceeded the standard when more than 5% of ashes were added. For As, the leaching concentration did not excess the standard both for forest soil and burnt sand if application doses were not more than 5%.