Proposed is a gas discharge valve for a packaging material, the gas discharge valve being attached on an upper surface of a packing material in a manner that covers a through-hole formed in one side of the packing material and being configured to discharge to the outside thereof only gas within the packing material, the gas discharge valve including: a high-adhesiveness layer attached to an external surface of the packing material and adhered to a portion of the external surface in the vicinity of the through-hole; and a low-adhesiveness layer formed inside the high-adhesiveness layer and adhered to cover a top opening of the through-hole, where, when gas occurs within the packing material, the low-adhesiveness layer is inflated by pressure, a portion thereof is raised, and the gas is discharged, and when the pressure is released, the low-adhesiveness layer seals the through-hole, thereby blocking introduction of outside air.