A flexible printed circuit board that is intended to minimize curling is formed having a first polyimide-resin layer with a conductor pattern formed on one surface thereof and supporting that conductor pattern. A second polyimide-resin is formed on another surface of the conductor pattern and covers and protects the circuit of the conductor pattern. The polyimide-resin layers are chosen so that a difference between a coefficient of linear thermal expansion of the first polyimide-resin layer and the coefficient of linear thermal expansion of the second polyimide-resin layer is 3×10−6/K or smaller.