A packaging container comprises an openable outer case and a bag for packaging a resin material in the outer case. The bag is partially turned back at fold portions so that part of the bag is turned inside out, and at least part of the out-turned part is fixed as a fixing part to any part other than the bag. The inner surfaces of the bag at the fold portions are placed in contact with each other, forming a contact portion, to seal the resin material. The contact portion is placed in correspondence with an openable part of an opening flap of the outer case.