PURPOSE: To provide the subject method capable of effectively producing pulp from a dismounted material chip remarkably low in water content and containing many voids in the chip according to the caustic cooking method by using a continuous digester equipped with a general steaming vessel widely used until now.

CONSTITUTION: From a dismounted material generated in dismounting a house, etc., and having 12 to 30wt.% water content, chips are made. The resultant chips are treated so as to make water adhere to the surface of the chips. Steam is subsequently sprayed onto the chips under atmospheric pressure so as to control the water content of the dismounted material chips to 35 to 50wt.%. The obtained dismounted material chips are then subjected to the caustic cooking treatment by using a conventional continuous digester equipped with a steaming vessel so as to produce the objective pulp.