A base station apparatus in a point-to-multi point radio communication system includes a directional antenna, a terminal station apparatus direction calculator, an antenna direction calculator, and an antenna direction adjuster. The directional antenna has directivity. The terminal station apparatus direction calculator calculates directions of the plurality of terminal station apparatuses relative to a position of the base station apparatus based on positions of the plurality of terminal station apparatuses and the position of the base station apparatus. The antenna direction calculator calculates a direction toward which the directional antenna should be oriented based on the directions of the plurality of terminal station apparatuses, channel quality of each of the plurality of terminal station apparatuses, necessary channel quality indicating the channel quality required by each of the plurality of terminal station apparatuses, and a directional pattern of the directional antenna. The antenna direction adjuster orients the directional antenna toward the direction.