An aerial-staying type communication relay apparatus having a relay communication station for relaying radio communication of terminal apparatuses located in plural, N, cells formed toward a service area on a ground and an antenna for service link, the communication relay apparatus comprising: position estimation means configured to estimate positions of plural terminal apparatuses located in the service area; parameter optimization means configured to divide plural, L, kinds of antenna parameters of the antenna for service link into plural parameter groups, and optimize the antenna parameters based on estimation results of positions of the plural terminal apparatuses, for each of the parameter groups, so that a desired communication quality can be obtained in the entire service area; and parameter application means configured to apply, to the antenna for service link, optimum values of the plural, L, kinds of antenna parameters after completing the optimization for each of the parameter groups, wherein the parameter optimization means are configured to divide the plural, L, kinds of antenna parameters of the antenna for service link into a first parameter group including horizontal beam directions of plural, N, beams forming the plural cells and a second parameter group including one or more other kinds of antenna parameters other than the horizontal beam directions of the plural, N, beams, and the parameter optimization means are configured to: determine the horizontal beam directions of the plural, N, beams belonging to the first parameter group based on the estimation results of the positions of the plural terminal apparatuses; and determine optimum values of the one or more other kinds of antenna parameters belonging to the second parameter group based on the estimation results of the positions of the plural terminal apparatuses by a search-based algorithm; characterized in that the parameter optimization means are configured to determine the horizontal beam directions of the plural, N, beams so that p < N beams among the plural, N, beams are disposed in the horizontal direction where the cluster of the terminal apparatus is occurred, and remaining N-p beams are disposed so that spatial intervals in an angular range of the horizontal direction excluding the p beams become equal to each other. position estimation means configured to estimate positions of plural terminal apparatuses located in the service area; parameter optimization means configured to divide plural, L, kinds of antenna parameters of the antenna for service link into plural parameter groups, and optimize the antenna parameters based on estimation results of positions of the plural terminal apparatuses, for each of the parameter groups, so that a desired communication quality can be obtained in the entire service area; and parameter application means configured to apply, to the antenna for service link, optimum values of the plural, L, kinds of antenna parameters after completing the optimization for each of the parameter groups, wherein the parameter optimization means are configured to divide the plural, L, kinds of antenna parameters of the antenna for service link into a first parameter group including horizontal beam directions of plural, N, beams forming the plural cells and a second parameter group including one or more other kinds of antenna parameters other than the horizontal beam directions of the plural, N, beams, and the parameter optimization means are configured to: determine the horizontal beam directions of the plural, N, beams belonging to the first parameter group based on the estimation results of the positions of the plural terminal apparatuses; and determine optimum values of the one or more other kinds of antenna parameters belonging to the second parameter group based on the estimation results of the positions of the plural terminal apparatuses by a search-based algorithm; characterized in that the parameter optimization means are configured to determine the horizontal beam directions of the plural, N, beams so that p < N beams among the plural, N, beams are disposed in the horizontal direction where the cluster of the terminal apparatus is occurred, and remaining N-p beams are disposed so that spatial intervals in an angular range of the horizontal direction excluding the p beams become equal to each other. determine the horizontal beam directions of the plural, N, beams belonging to the first parameter group based on the estimation results of the positions of the plural terminal apparatuses; and determine optimum values of the one or more other kinds of antenna parameters belonging to the second parameter group based on the estimation results of the positions of the plural terminal apparatuses by a search-based algorithm; characterized in that the parameter optimization means are configured to determine the horizontal beam directions of the plural, N, beams so that p < N beams among the plural, N, beams are disposed in the horizontal direction where the cluster of the terminal apparatus is occurred, and remaining N-p beams are disposed so that spatial intervals in an angular range of the horizontal direction excluding the p beams become equal to each other.