To provide a separation treatment method which eliminates following difficulties and enabling to recycle a wall paper, since recycling (reuse of resource) is extremely difficult since a bat generated in a manufacturing factory where it is mass-produced or at execution and further the plastic wallpaper discarded accompanying with reforming of a residence or the like are in the state that the paper, i.e., a base material and the plastic are completely closely adhered.

The portion of paper, i.e., the base material of the plastic wallpaper is separated/decomposed using an enzyme commercially available as a fiber modifying enzyme or a cellulolytic enzyme. Recycling of the wallpaper is enabled by separating it from the plastic.