To improve sensitivity at an RF receiving side and to mount an RF transmitting antenna while saving a space, in a communication apparatus including an LF receiving antenna and the RF transmitting antenna.

The LF antenna 22 is housed inside a resin case 31, thereby being configured as a surface-mounted component. Furthermore, in an outer circumferential portion of the resin case 31, a metallic lead wire 24A is provided. The lead wire 24A forms an RF antenna together with a conductor pattern 24B formed on a printed wiring board 33 when the LF antenna 22 is surface-mounted on the printed wiring board 33. In such a structure, differently from the RF antenna constituted of only a planar conductor pattern on the printed wiring board, a radio wave having a polarization plane, that is not in parallel with the printed wiring board, is also generated, thereby suppressing receiving sensitivity reduction at the side of an in-vehicle unit 1.