PURPOSE: To facilitate manufacture of a longer size flexible printed board with existing equipment by a method wherein a third board part which connects a first board part to a second board part is provided and the connected flexible printed board parts are properly folded.

CONSTITUTION: A first board part 1, a second board part 2 and a third board part 3 which connects the first board part 1 to the second board part 2 are provided. A double-sided adhesive tape 30 with required dimensions is applied to the surface or the rear of the third board part 3 with which the end parts of the first board part 1 and the second board part 2 are connected to each other. The second board part 2 is folded 180 degrees and bonded to fix. The third board part 3 is so folded as to hold the double-sided adhesive tape 30 between the folded parts. By providing the double-sided adhesive tape 30, the first and second board parts 1, 2 are connected to each other and fixed in the form of one row and a longer side flexible printed board is realized. With this constitution, as the longitudinal dimensions of the respective board parts are short, the longer size flexible printed board can be manufactured with existing equipment.