Abstract: A plain layer in a forming area of a measuring wiring pattern is patterned so that its copper-containing amount may be coincided with a copper-containing amount in a forming area of a measurement target signal wiring pattern. Thereby, it is possible to coincide a thickness of an insulating layer in the forming area of the measuring wiring pattern with a thickness of the insulating layer in the forming area of the measurement target signal wiring pattern, thus reducing a measuring error of the characteristic impedance based on a difference of a thickness of the insulating layer. Using the measuring wiring pattern, it is possible to measure a correct characteristic impedance of the measurement target signal wiring pattern.