A method for manufacturing an intermediate material for a soft packaging container according to the present invention includes: a first overlaying step P1 of laying a second raw film sheet 120 over a first raw film sheet 110; a confining portion forming step P2 of forming a filler confining portion 50 for confining a filler 59, the filler confining portion 50 being constituted by a non-joined region between the first raw film sheet 110 and the second raw sheet 12, by joining a portion of the first raw film sheet 110 and a portion of the second sheet 12 to each other; a folding step P4 of folding the first raw film sheet 110 and the second sheet 12 with the first raw film sheet 110 on an outer side, such that the filler confining portion 50 is present in a state where an inner portion thereof is continuous on two sides that are connected via at least one folding position; an accommodating portion forming step P5 of forming an accommodating portion 60 by joining a plurality of portions including at least one of the first raw film sheet 110 and the second sheet 12; and a cutting step P6 of forming an intermediate material A1 for a soft packaging container by cutting at least the first raw film sheet 110. This configuration makes it possible to more readily and reliably manufacture a soft packaging container that has a filler confining portion in more regions.