To provide a magnetic communication antenna and an apparatus which possess a long communication range and can be installed in a limited space.

The magnetic communication antenna 1, which converts electric signals sent from a signal source to a magnetic field B of a prescribed resonant frequency f0and radiates it, is composed of a series resonant circuit 2, which has a prescribed resonant frequency f0containing a feeding terminal 12 connected to the signal source and a first coil 3, and a series resonant closed circuit 5, which has a prescribed resonant frequency f0containing a second coil 6 magnetically coupled with the first coil 3. It is preferable that the first coil 3 and second coil 6 are disposed on a coaxial line, an axial space W between the first coil 3 and second coil 6 and/or a δ/D diameter ratio of the second coil to first coil is determined so as to make the peak frequency of the magnetic field B, which is emitted or absorbed, identical to the prescribed resonant frequency f0. Furthermore, it is preferable that a transmission circuit 14, which modulates carrier waves of the prescribed low frequency f0with the measuring signals of a measuring instrument 17 and outputs the modulated carrier waves, is connected to the feeding terminal 12, and the resonant circuits 2 and 5 are adjusted so as to make their resonant frequencies identical to the frequency f0of the carrier waves.

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