Abstract: A paperboard material 101 is mainly composed of a paperboard having a weight of 200 to 450 g/m.sup.2, a density of 0.65 to 0.82 and a gas permeability of 50 to 200 sec. A first resin layer having liquid-impermeability and thermal resistance is formed entirely on the surface of the paperboard on the inner side of the receptacle, and a second resin layer having permeability to gas and liquid is formed entirely on the back surface of the paperboard. Radial score lines 117 are formed in the portion corresponding to the corners of the paperboard material 101 toward its outer periphery. The score lines 117 do not reach the outer periphery of the paperboard material 101 but terminate at the position at a distance "a" (1 to 3 mm). The score lines 117 are formed by pressing the paperboard with a pressing die from the side constituting the inner side of the receptacle toward the outer side.