There are provided a package bag capable of surely preventing stay of ambient air or the like in the package bag and intake thereinto even in the filling by handwork or the like of an operator as well as a method for filing and packing the liquid material to be packed into the package bag. A package bag is characterized by comprising a bag main body made of thin laminate films for packing, a fusion part formed at a position spaced from a bottom portion of the bag main body not forming a nozzle through fusion and extending in a widthwise direction of the bag main body, an insert port for a pipe-like filling nozzle provided in a middle portion of the fusion part, a filling part of one-way function formed between the fusion part and an opening end of the bag main body.