To maintain optimum adaptability when an interval between lines is reduced due to miniaturization by forming the mutually opposed edges of two adjacent microstrip lines floating from a dielectric substrate and providing a dielectric of a permittivity smaller than that of the dielectric substrate under it.

The mutually opposed edges of the two adjacent microstrip lines 3 and 4 floating with respect to the dielectric substrate 2 and the dielectric 10 of the permittivity smaller than that of the substrate 2 is formed under it and between the lines 3 and 4. Then, the lines 3 and 4 are arranged to be adjacent mutually. At the time of inputting the signal of a frequency making the length of the lines 3 and 4 a 1/4 wave length from an input terminal, a part of the inputted signal is outputted from an output terminal 6 through the line 3 and the remainder is transmitted to the line 4 and outputted from an output terminal 7.