A signal carrying apparatus (101) for transmitting a signal by variation of electromagnetic field comprises a meshed first conductor portion (111) which serves as a conductor in the frequency band of the electromagnetic field, and a second conductor portion (121) of which external shape is sheet-like and which serves as a conductor in the frequency band of the electromagnetic field and arranged substantially in parallel with the first conductor portion (111). In the interval region (131) between the external shape of the first conductor portion (111) and the external portion of the second conductor portion (121), and in the planar leak region (141) located oppositely to the interval region (131) across the external shape of the first conductor portion (111), the electromagnetic field propagating in that frequency band has a strength attenuating exponentially with the distance from the external shape of the first conductor portion (111) in the leak region (141).