The author investigated the cause of fungus growth on the surface of decorative paintings of wooden buildings and its prevention. Fungi found on the surface of paintings were >Cladosporium herbarum, Aspergillus sp. And >Penicillium sp., and their growth had no relation to pigments used, but was supported by the glue used as an adhesive for the pigments. A test of spraying fungicide showed that a 0.5% ethanolic solution of thiabenzazole sprayed on the surface in the amount of 50 ml./m.2>s was effective. P-Chloro-m-xylenol, when used in an aqueous solution of glue at concentrations of 0.5imilar>1.0% of glue on dry basis, was found to be an extremely effective fungicide. The effect of these fungicides on pigments was also studied.