The invention discloses a joint method utilizing thermoplastic double-sticky tape and a portable electronic device. In a case of joining a display panel and a machine body of the portable electronic device, an environmental load is reduced by means of lowering an obsolete quantity of double-sticky tapes, and waterproof performance between the display panel and the machine body is ensured. Double-sticky tapes (4A, 4B) are arranged in a box shape in a combined mode. The front end side portions of the double-sticky tape (4A, 4B) are superposed with each other in a thickness direction, and the thickness of the superposed part is made to be the same as the non-overlapping part. The width of the superposed part is made to be smaller than the non-overlapping part, so that the profile of the box shape formed by the double-sticky tape (4A, 4B) can be restrained in a tolerance zone.
