To reduce an electromagnetic coupling between a distributed constant line and a power supply line for a smaller circuit, related to a high-frequency circuit which uses a distributed constant line of multilayer structure.

The electromagnetic field coupling between a power supply line 5 and a first layer distributed constant line 3 as well as a second layer distributed constant line 4 which comprise a required high-frequency characteristics in electromagnetic coupling is reduced by a through hole 8, to which the electric potential connecting ground patterns 6 and 7 are grounded. Thus, no electromagnetic coupling occurs even if the power supply line 5 is wired close to the first layer distributed constant line 3 and second layer distributed constant line 4, causing no degradation in required high-frequency characteristics of the distributed constant lines 3 and 4.