PURPOSE: To provide a multilayered thick paper product usable even in aseptic packing and made usable as liquid packing thick paper proper to the recycle of a raw material in a usual pulper by constituting the product by including a plastic layer having mechanical strength capable of being substantially integrally removed in pulping treatment.

CONSTITUTION: A plurality of plastic layers are formed on the undersurface of the main layer of a thick paper product, that is, on the surface coming into contact with an article to be packed. These plastic layers starting from the thick paper layer 1 are an LDPE layer 5, the bonding layer 6 comprising, for example, modified polyethylene formed on the surface thereof, the barrier layer 7 of ethylene vinyl alcohol or EVOH formed on the surface thereof, the second bonding layer 8 similar to the first bonding layer comprising modified polyethylene formed on the surface thereof and the layer 9 like LDPE finally formed on the surface of the layer 8 to be brought into contact with the product.