To provide a hands-free communication apparatus capable of improving its merchantability by utilizing the hands-free communication apparatus in an unused state as a crime preventing device.

This hands-free communication apparatus for performing the hands-free communication of a telephone set (portable telephone) A is provided with: a hands-free unit 1 loaded on a vehicle for performing radio communication with a telephone set A by radiating radio waves; an electric field strength detection part 3 arranged at a position where a radio wave from the hands-free unit 1 can be received; and a control part 2 for calculating electric field strength detected by the electric field detection part 3, and for setting the hands-free unit 1 in a hands-free mode for performing hands-free communication with the telephone set A when it is determined that the electric field strength is a predetermined value or less as an arithmetic result, and for setting the hands-free unit 1 in a security mode for monitoring the vehicle when it is determined that the electric field strength is larger than the predetermined value from the arithmetic result.