The present invention provides a synthetic wood including a body containing a polystyrene- or polypropylene-based resin as the major component and a weather-resistant outer layer with excellent adhesion to the body. A synthetic wood 1A includes a body 2 defining a core thereof and formed of a polystyrene or polypropylene foam and an outer layer 3 covering the body and formed of a weather-resistant synthetic resin that is unfoamed or foamed at a low expansion rate. The body and the outer layer are integrally bonded by coextrusion. The body contains a polystyrene- or polypropylene-based resin as the major component. The outer layer contains an acrylonitrile-acrylic rubber-styrene copolymer and/or an acrylonitrile-ethylene propylene rubber-styrene copolymer, which are weather-resistant resins, as the major component. The outer layer further contains the major component resin of the body as a minor component in such an amount that the minor component contributes to the enhancement of the adhesion between the body and the outer layer without impairing weather resistance.