Disclosed is an antenna apparatus, including: a support member; a drum which is rotatably supported by the support member and whose outer circumference corresponds to faces of polygonal column; a case which covers the support member and the drum and which has a hole along a circumference direction of the drum; an antenna rod which extends from the outer circumference of the drum in a direction perpendicular to an axis of the drum toward an outside of the case through the hole of the case, and polyhedral faces which are provided inside the case and which are to be fitted into the outer circumference of the drum.