The chemical properties of oak tree wood vinegar and the effect of wood vinegar on the tomato seedling were investigated to apply wood vinegar efficiently to the organic 󰠏 and natural farming system. On the basis of the results from chemical properties of the oak tree wood vinegar, mineral nutrient contents of wood vinegar was low. Therefore, wood vinegar could not be a suitable nutrient source for the plant growth at 500~1000 times dilution level, which commonly used in the farming, if only wood vinegar is supplied for the nutrient source for the plant growth. The application of wood vinegar increased root growth up the 500 times dilution level while decreased shoot growth. Furthermore, the anion concentrations such as nitrate and phosphate of the plant were decreased by the application of wood vinegar while cation concentrations such as K, Ca, and Mg were increased. Phenolic compounds of wood vinegar such as chlorogenic acid and ferulic acid enhanced the root growth. Interestingly the application of ferulic acid increased both root and shoot growth at the level of 10⁻⁴M concentration. It indicated that the effect of wood vinegar on the production of healthy plant seedling may be due to the beneficial root growth by phenolic compounds such as chlorogenic acid and/or ferulic acid of the wood vinegar. However, the effect of the wood vinegar on the plant growth could be influenced by synergism or antagonism of different phenolic compounds in wood vinegar used. In addition, drench in the soil of wood vinegar may be more beneficial compared to foliar application for the improvement of root activity and plant growth.