To develop wood ash recycling to the forest, component of wood fuel material, and fertilizer and micro element concentration of wood ash generated from wood biomass burning boiler were investigated. In the fuel material, wood chip was highest and sawdust and bark were lower component than chip. PKS were always contained 10% of total weight. These components did not fluctuated during sampling. In the wood ash, potassium contents were 4-8%, and water soluble potassium were 1-2%, and it also contains 1-2% of phosphorus. Silicate was highest elements and its concentration was 50-60%. Total from of heavy metal concentration in all elements were under the limit of environmental standard, but some element such as fluorine and boron were over the limit in some ash. To stabilize the nutrient concentration in the wood ash, it is necessary to keep a components of fuel material for burring.
