PURPOSE: To obtain wood preservative having excellent antiseptic effect by a method wherein the specified percentage of dibutyl phthalate is added as antiseptic component to wood preservative.

CONSTITUTION: Dibutyl phthalate as antiseptic component is added by 20wt.% to wood preservative. In addition, antiseptic component excluding dibutyl phthalate is added and, further, alkyd resin is also added to the wood preservative. The wood preservative is used by spraying or applying to the surface of the wood or by immersing of in the form of medicine such as oily medicine, emulsion, suspension, frothy medicine, pasty medicine or the like. As other antiseptic component, organic iodine-based antiseptic, benzimidazole- or benzothiazole-based antiseptic and triazole-based antiseptic can be added. Furthermore, insecticide such as organophosphor-based one, carbamate-based one, pyrethroid-based one, insect-repellent and efficacy intensifier may well be added.