A natto (fermented soybeans) container 11 is made of a resin-foam sheet of a structure of which a lid body, having a natto-holding recess, is connected by a hinge part to, and covering the opening of the container body. A seasoning-holding recess is provided adjacent to the inner-lid surface of the lid body. A pre-defined folding line L1 is described on the outer-lid surface of the lid body, along which the lid body folds upward into a valley shape. A splittable groove, provided on the lid body, communicates with the natto seasoning-holding recesses and crosses the pre-defined folding line L1. A sealant material is provided on the outer-lid surface, covering and sealing the seasoning holding recess. Hence, the lid body folds into a valley-shape along the pre-defined folding-line crossing, thus breaking the splittable groove.
