A touch panel sensor with which unevenness of interference can be reduced is provided. A touch panel sensor of the present invention includes a film base material, a first transparent electrode pattern formed on a first face of the film base material, a first adhesive layer laminated on the first face of the film base material so as to cover the first transparent electrode pattern, a second transparent electrode pattern formed on a second face of the film base material, and a second adhesive layer laminated on the second face of the film base material so as to cover the second transparent electrode pattern, and the film base material has an in-plane phase difference of λ/4 with respect to a wavelength λ in the visible light region.