To provide a method for manufacturing a used paper foamed molded product by an in-mold molding process wherein a foamable raw material comprising a paper type foaming material, which is prepared by mixing a foaming agent with a used paper material and a foamable synthetic resin material or a material comprising waste foamed styrol ground to be reduced in volume, is foamed in a mold under heating in a heating process and cooled in a cooling process to obtain the foamed molded product.

In the in-mold molding method, the foamable raw material (c) containing the used paper material is charged in molds 1 and 2 provided with small holes and foamed under heating in the heating process by an ordinary reduced and normal pressure method to mold a foamed molded object which is, in turn, cooled in a waste cooling process using cooling water (b) or a natural cooling process to manufacture the foamed molded product. The used paper material and the foamable synthetic resin material of foamed particles or prefoamed particles or a material prepared by mixing the foaming agent with a material comprising waste foamed styrol ground to be reduced in volume are mixed in an almost equal ratio to form the foamable raw material which is, in turn, charged in the mold to be subjected to in-mold molding.