A circuit board includes a film substrate, a plurality of wiring layers arranged in order on the film substrate, and bumps formed on the wiring layers, respectively. Each of the bumps is provided across a longitudinal direction of a corresponding one of the wiring layers so as to extend over regions on both sides of the wiring layer above the insulating substrate, and a cross sectional shape of the bump taken in the width direction of the wiring layer is such that a central portion is higher than portions on both sides of the central portion. Accordingly, the bumps formed on the wiring layers can be held with strength sufficient for practical use against the force applied in the lateral direction.