PURPOSE: To extremely improve efficiency in separation effects on foreign materials such as tacky agents and adhesives in cleaning steps and obtain reclaimed pump without any trouble in sheet-forming steps by specifying the amount of the foreign materials in a pulp slurry prepared by disintegrating waste paper containing the above-mentioned foreign materials.

CONSTITUTION: Waste paper containing tacky agents, adhesives and/or plastics is initially disintegrated. In the process, the disintegration degree of the waste paper is regulated so as to provide the total number of ≤10 pieces of the tacky agents, adhesives and plastics in the pulp based no 20g dried pulp in passing the resultant pulp slurry prepared by disintegrating the aforementioned waste paper through an experimental flat screen equipped with a screen having slits with 8/1000 inch width. The pump slurry with the specified content of the foreign materials such as the tacky agents is then subjected to cleaning treatment with a screening machine having slits of mesh openings with ≤0.5mm width in a plate to afford reclaimed pulp.