To provide a packaging container which is made up by using a polyester-laminated paper stuff resistive against discoloration at heat sealing on manufacturing and reheating at the time of use.

A blank made up by laminating a thin film of heat sealing polyester in a thickness of 5-100 μm having a branching chain resistive against heating in an oven for ten minutes or more at the temperature less than 230°C on at least one side of both of the surface and reverse side of a paper stuff is used. Lugs on both sides of the blank are put together with the laminated face put inside, and a side wall is formed with adhesion made at the temperature of 230°C or more. A bottom wall in which a peripheral flange is formed out of the laminated blank with the laminated face put inside is formed out of the laminated blank. The peripheral flange of the bottom wall fitted into the lower end of the side wall and the lower end of the side wall are stuck together by heating and pressing for 0.3 seconds or more at the temperature of 230°C or more.