PROBLEM TO BE SOLVED: To provide a wood preserving agent composition allowing to measure an infiltrating degree of the treatment chemical without blending a heavy metal as a color indicator into a treatment chemical, and further, a method of measuring an infiltrating degree of the wood preserving agent composition into a woody material.SOLUTION: The infiltrating degree is measured using a leuco dye which is colored by an electron acceptive material contained in the treatment chemical as an indicator.COPYRIGHT: (C)2008,JPO&INPIT【課題】処理薬剤中に重金属を呈色剤として配合せずに、薬剤処理剤の浸潤度が測定できる木材保存剤組成物を提供し、更に該木材保存剤組成物の木質材料への浸潤度を測定する方法を提供すること。【解決手段】処理薬剤に含有される電子受容性物質によって発色するロイコ染料を指示薬とすることで、浸潤度を測定できるようにした。【選択図】なし