To obtain a heat-insulating sheet made of paper wherein paper recycling may not be obstructed and aluminum may not remain as dust after incineration by forming a smooth reflection face due to transfer of an extremely thin layer of aluminum vapor deposition on at least one of paper members among a liner and a core of corrugated fiberboard.

An extremely thin layer 4 of aluminum vapor deposition is transferred on an cuter face of a surface liner 2 for double-faced corrugated fiberboard having liners 2, 3 on both faces of a core 1, and a heat-insulating sheet S having a mirror-like reflection face 5 is formed. The extremely thin layer 4 of transferred aluminum vapor deposition is formed by vacuum-deposit aluminum particles on a transfer plastic film, and adhesive is applied on an aluminum deposited face to transfer onto a paper face. Although a face 6 adhered to the paper is relatively rough in this case, an outer face which has been deposited to the film is formed as the extremely smooth reflection face 5. Thus significant heat insulation due to reflection of radiation heat can be obtained, while recycling and incineration of the paper may not be obstructed since the aluminum layer is an extremely thin layer with a very small quantity.