To provide a packaging container and its manufacturing and assembling method which allow the removal of the packaging container one by one from an assembly of packaging containers when an article is put in the packaging container to enable production with no decrease in production efficiency, and provide a less bulky assembly when the packaging containers are recovered for recycling after being used up.

The packaging container comprises a bottom, a first peripheral wall rising from the periphery of the bottom, and blocking preventive ribs which are formed on the bottom in integral thereto and have respective surrounding second peripheral walls. At least two ribs are formed to be nonsymmetrical with respect to the center of the bottom, and each rib has the height that is defined by the inequality (1) shown below that express the relationship among the thickness of the material of the container, the height of the first peripheral wall, and respective taper angles of the first and second peripheral walls: (1) H>h≥(t/sinθmin)-t, where H is the height of the first peripheral wall, h is the height of the rib, t is the thickness of the material, and θmin is the minimum taper angle among the taper angles of the first and second peripheral walls.