A flexible printed circuit comprising a plastic film and a conducting layer, wherein the plastic film exhibits a heat shrinkage rate ellipse having an eccentricity of not more than 0.7 and preferably exhibits an ultrasonic wave propagation rate ellipse having an eccentricity of not more than 0.4 and a polarized microwave transmission intensity ellipse having an eccentricity of not more than 0.55. The flexible printed circuit has improved dimensional accuracy owing to the dimensional stability of the plastic film.