The invention relates to a wood preservative, which wood preservative contains vegetable oils processed from crude tall oil, such as resin acids and fatty acids. The wood preservative according to the invention is characterized by that the wood preservative is crude tall oil, from which have been removed neutral components contained by the crude tall oil, especially compounds acting as the breeding ground and nutriment of rot fungi and/or compounds causing esterification reactions, such as fatty alcohols and/or steroid groups, such as sitosterol and sitostanol. The invention also relates to a method for manufacturing wood preservative according to the invention.