A method for manufacturing a structure of flexible printed circuit boards (150, 160), the structure comprising: an organic light emitting diode including a rectangular substrate that includes a display portion for displaying an image and a non-display portion positioned on an outer side thereof, the method comprising: 1) installing two or more flexible printed circuit boards at edges of the rectangular substrate in the non-display portion; and 2) making the flexible printed circuit boards having neighboring end portions conduct electricity using soldering; wherein the step 1) is a step of installing a pair of lower flexible printed circuit boards facing each other at edges of the rectangular substrate in the non-display portion and mounted with anode pads and cathode pads, and a pair of upper flexible printed circuit boards facing each other at edges of the rectangular substrate to partially overlap the lower flexible printed circuit boards and mounted with anode pads and cathode pads, and the step 2) is a step of forming holes in a portion of the upper flexible circuit board that overlaps the lower flexible printed circuit board, and making the anode pads and the cathode pads of the upper flexible printed circuit boards and the anode pads and the cathode pads of the lower flexible printed circuit boards, which overlap each other, conduct electricity by solder that fills the holes through soldering, wherein the upper flexible printed circuit board and the lower flexible printed circuit board have a multilayer structure including two or more layers; and wherein an outermost layer of the upper flexible printed circuit board is installed to extend in the length direction of the upper flexible printed circuit board, and is positioned on the lower flexible printed circuit board so that an end portion of the outermost layer of the upper flexible printed circuit board overlaps the lower flexible printed circuit board. 1) installing two or more flexible printed circuit boards at edges of the rectangular substrate in the non-display portion; and 2) making the flexible printed circuit boards having neighboring end portions conduct electricity using soldering; wherein the step 1) is a step of installing a pair of lower flexible printed circuit boards facing each other at edges of the rectangular substrate in the non-display portion and mounted with anode pads and cathode pads, and a pair of upper flexible printed circuit boards facing each other at edges of the rectangular substrate to partially overlap the lower flexible printed circuit boards and mounted with anode pads and cathode pads, and the step 2) is a step of forming holes in a portion of the upper flexible circuit board that overlaps the lower flexible printed circuit board, and making the anode pads and the cathode pads of the upper flexible printed circuit boards and the anode pads and the cathode pads of the lower flexible printed circuit boards, which overlap each other, conduct electricity by solder that fills the holes through soldering, wherein the upper flexible printed circuit board and the lower flexible printed circuit board have a multilayer structure including two or more layers; and wherein an outermost layer of the upper flexible printed circuit board is installed to extend in the length direction of the upper flexible printed circuit board, and is positioned on the lower flexible printed circuit board so that an end portion of the outermost layer of the upper flexible printed circuit board overlaps the lower flexible printed circuit board.