To provide an antenna apparatus which is capable of preventing interference of a reflection wave and a direct wave and receiving a required direct wave while increasing its level.

A radio wave to be received by an antenna is diffracted at a terminal portion of an obstacle. In such a case, when the distance between a transmitter which transmits a radio wave to the antenna and the terminal portion of the obstacle is defined as d1, the distance between the terminal portion of the obstacle and the antenna is defined as d2, the distance from an apparent straight line connecting the transmitter and the antenna to the terminal portion of the obstacle is defined as (h) and a wavelength of the radio wave is defined as , the obstacle and the antenna apparatus are disposed in such a way that the value of a diffraction parameter calculated by an expression (1) satisfies the condition of -1.5-0.7.