To reutilize a thermoplastic synthetic resin product of every kind to recycle the same as a wooden synthetic panel by respectively compounding a cellulosic crushed material such as wood flour or the like, a resin and a dispersion accelerator in a specific amt. ratio and crosslinking the cellulosic crushed material and the resin through the dispersion accelerator.

A cellulosic crushed material with a moisture content of 0.3 wt.% and an average particle size of 50-300 meshes (about 300-50 μm) such as wood flour and a resin are compounded in a wt. ratio of 50-60% and a dispersion accelerator is compounded in an amt. of 0.3-1.0% by wt. of the wood flour and the resin to crosslink the cellulosic crushed material and the resin through the dispersion accelerator. Further, it is pref. to compd. 50-60 wt.% of the wood flour as the cellulosic crushed material and 50-40 wt.% of polycarbonate, nylon or PVC as the resin. Furthermore, if titanium oxide is compounded in an amt. of 25% or less by wt. of the wood flour, coloration and the yellowing of wood can be prevented. As the resin, a waste material of a thermoplastic synthetic resin product can be reutilized.