PURPOSE: To provide a constitution that the higher harmonic radiation from a high frequency circuit is suppressed and a unified molding is possible without an adjustment, in a high frequency circuit integrated small antenna.

CONSTITUTION: In a high frequency circuit integrated small antenna having a waveguide part 3 having a vibration proof device 2 which is continuous to a high frequency circuit 1 and an opening form antenna 4 which is continuous to the waveguide part 3, a waveguide corner 8 is provided between the waveguide part 3 and the opening form antenna 4. The higher harmonic components radiated from the high frequency circuit 1 via the vibration proof device 2 is made to attenuate by the transmission characteristic of the waveguide corner 8 and unnecessary high harmonic can be suppressed. As the waveguide corner 8 is only added, a high harmonic suppressing antenna having a constitution that a unified molding is possible without an adjustment can be provided.