A paper container for fluid substances. It comprises: a tapered trunk portion formed by rolling a sheet comprising a layer having a barrier ability applied onto a surface of cardboard, in a state in which the layer is disposed inside, and by joining longitudinal-directional ends of the sheet with each other; and a bottom member formed from a disk-shaped sheet comprising a layer having barrier ability applied onto a surface of cardboard, a lower end portion of the trunk portion and a peripheral portion of the bottom portion member being engaged and jointed with each other in such a manner that the respective layers face each other. A first end portion for forming a joint portion of the trunk portion has an extending film which surrounds an end surface of the cardboard and reaches an external surface of the cardboard. A second end portion of the joint portion has a stepped portion which bends outside from an end-surface position of the first end portion and which extends along an external surface of the first end portion. An inner film of the second end portion are directly or indirectly joined with the extending film of the first end portion.