Problem to be solved: to provide a cardboard coffin with excellent stability of a box shape which is difficult to be deformed even when subjected to a load load and is hard to be deformed due to changes in temperature and humidity. The cardboard coffin 10 comprises a box body 12 formed by bending the expansion sheet of the reinforcing cardboard material and a bracing plate 16 for reinforcing the box shape of the box body 12. The box body 12 is provided with a rectangular bottom plate 12a, a rectangular side plate 12b which is substantially vertical to the right and left sides of the bottom plate 12a in the longitudinal direction, and a rectangular mower 12C, which is raised substantially vertically in the longitudinal direction of the bottom plate 12a in the longitudinal direction, in the box body On the other hand, there is provided a reinforcing plate 16 made of reinforced corrugated cardboard which projects the side wall surface and the bottom plate wall in the center of the longitudinal direction. The intersecting plate 16 is a strip like plate which extends in the longitudinal direction of the box body 12 with a constant width and thickness, and is provided with an inclination of approximately 45 degrees between the side plate 12b and the bottom plate 12a with the space below the band like plate. Diagram【課題】荷重負荷を受けても歪みにくく、温度や湿度の変化により変形しにくい箱形状の安定性に優れた段ボール棺を提供する。【解決手段】段ボール棺10は、強化段ボール材の展開シートを折り曲げることにより形成される箱体12と、この箱体12の箱形状を強化するための筋交い板16とを備える。箱体12は、矩形の底板12Aと、この底板12Aの長手方向の左右にほぼ垂直に立ち上げられる矩形の側板12Bと、底板12Aの長手方向の前後にほぼ垂直に立ち上げられる矩形の妻板12Cとを備え、箱体12の内側底部の左右隅であって長手方向の中央部に、側板壁面と底板壁面とを突っ張る強化段ボールからなる筋交い板16が設けられる。筋交い板16は、一定の幅と厚みをもって箱体12の長手方向に連なる帯状の板であり、当該帯状の板の下方に空間を伴って側板12Bと底板12Aとの間にほぼ45゜の傾斜をもって架け渡される。【選択図】図1
