A connection structure of Flexible printed circuits comprising: first and second Flexible printed circuits, respectively, including a base formed of a resin, a plurality of wiring patterns arranged side by side on the base, a cover film formed of a resin to cover opposite sides of the wiring patterns to the base, and a connection portion in which the plurality of wiring patterns are not covered by the cover film, the connection portions of the first and second Flexible printed circuits being connected with each other. The wiring patterns in the connection portions include a large width portion which is larger in width than the wiring patterns covered by the cover film. The large width portions on the first Flexible printed circuit and the large width portions on the second Flexible printed circuit are connected to each other by means of soldering.