A thin-film multilayered electrode (3) has a dielectric substrate (2); a ground conductor (6) provided on a back surface of the dielectric substrate (2); and a plurality of thin-film conductive layers (4a, b, c, d) and dielectric layers (5a, b, c) alternately stacked on a front surface of the dielectric substrate (2). The ground conductor (6), one of the thin-film conductive layers (4a) in contact with the dielectric substrate (2) and the dielectric substrate (2) interposed therebetween form a TEM mode principal transmission line (7), and each thin-film dielectric layer (5a) and a pair of thin-film conductive layers (4a, b) sandwiching the thin-film dielectric layer to form a TEM mode sub-transmission line. A thickness and a dielectric constant of each thin-film dielectric layer (5a, b, c) is set such that phase velocities of TEM waves which propagate through the TEM mode principal transmission line (7) and the TEM mode sub-transmission lines are substantially identical with each other. A thickness of each thin-film conductive layer (4a, b, c, d) is set at a predetermined value which is smaller than a skin depth at a predetermined operating frequency such that electromagnetic fields between the TEM mode principal transmission line (7) and its adjacent TEM mode sub-transmission line, and between each adjacent pair of TEM mode sub-transmission lines, are coupled with each other. At least one of the thin-film dielectric layers (5a) which is closest to the dielectric substrate (2) has a thickness greater than that of the other thin-film dielectric layers (5b, c).
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