The present invention provides a packaging material for a patch, the packaging material comprising: an inner layer film made of a polyethylene terephthalate-based resin having heat sealing properties; and a substrate film, wherein a heat-sealing surface of the inner layer film comprises an isophthalic acid-modified polyethylene terephthalate resin having a copolymerization ratio of isophthalic acid component of 10 mol % to 20 mol %. More preferably, the inner layer film made of the polyethylene terephthalate-based resin having heat sealing properties is a multi-layer film comprising at least two layers including a heat sealing surface side layer made of an isophthalic acid-modified polyethylene terephthalate resin having a copolymerization ratio of isophthalic acid component of 10 mol % to 20 mol % and a layer made of an isophthalic acid-modified polyethylene terephthalate resin having a copolymerization ratio of isophthalic acid component of 0 mol % to 5 mol %.