PURPOSE: To reduce the area of a high-frequency blocking circuit corresponding to the minimization of a microwave circuit, for example, concerning the high-frequency blocking circuit used for the equipments of microwave bands.

CONSTITUTION: At the high-frequency blocking circuit equipped with serially connected high-impedance and low-impedance λg/4 lines, a high-impedance λg/4 line 41 and a first ground conductor 42 are formed on the first layer P1 of a multilayered printed circuit board 8, a low-impedance λg/4 line 51 is formed on a second layer P2 and a third ground conductor 61 is formed on a third layer P3 respectively. In this case, however, the low-impedance λg/4 line is constituted so as to be held between the first and second ground conductors and to be connected through a through hole 7 to the high-impedance λg/4 line each other.