PURPOSE: To provide a preservative for wood with good storage stability even for high aliphatic hydrocarbon content by using a specific stabilizer for wood preservative containing a biocide insoluble in water and soluble in aliphatic or aromatic hydrocarbon solvent, and a mixed solvent of aliphatic and aromatic hydrocarbon.

CONSTITUTION: A biocide such as insecticide and antimold agent which is insoluble in water and soluble in aliphatic and/or aromatic hydrocarbon solvent, and a water-insoluble mixed solvent consisting of aromatic hydrocarbon of 5 to 20% by weight and aliphatic hydrocarbon of 95 to 80% by weight are used for this preservative. As a stabilizer, phenol, bisphenol or its derivative containing aryl or alkylaryl group and/or polyoxypolyphenyl alkane and/or phospholipid such as soybean lecithin of 0.005 to 15% by weight per 100 parts by weight mixed solvent is used, especially, bishydroxyarylalkane or its derivative is preferable. Coloring agents, synthetic resins, adhesives, processing auxiliaries, surfactants, desiccants, suspending agents, organic polar solvents and the like may be combined.