PURPOSE: To reduce the leakage of a radio wave to a back face of an antenna by forming a reflecting plane of an FRP reflection mirror with a conductive woven cloth made of glass fiber and providing a radio wave absorbing layer at the rear face of the reflecting plane.

CONSTITUTION: The conductive woven cloth 6 and the radio wave absorbing layer 7 are provided to the FRP forming curved face 4 of the FRP reflection mirror 1. Denoting the voltage reflecting rate of the conductive woven cloth 6 of the FRP reflection mirror 1 as γ, then the reflected power is proportional to γ2 and the remaining power proportional to (1-γ2) is transmitted. After the transmitted wave passes through the forming curved face 4 of the FRP, the wave is subjected to attenuation at the radio wave absorbing layer 7. Thus, the leakage of the radio wave from the FRP reflection mirror 1 to the antenna rear face is reduced.