An antenna apparatus detects a reflected light from a scattered light or from a reflector (40) mounted in an optical fiber (6,6a-6d), measures a strain generated in a primary reflecting mirror (1) and so on based on the scattered light or the reflected light, and calculates a reflector surface compensation data based on the strain of the primary reflecting mirror (1) and so on. An antenna driving section (11) is driven according to the reflector surface compensation data in order to compensate a direction of an antenna.