A locating apparatus , comprising: first radio communication information acquisition means requesting multiple installed devices installed within a given space (S) to radio-communicate with each other so as to acquire first radio communication information including-a parameter obtained for each pair of the installed devices for each of the installed devices ; first radio communication information storing means recording the first radio communication information acquired by the first radio communication information acquisition means for each of the installed devices ; second radio communication information acquisition means requesting a terminal to be located within the given space (S) and the multiple installed devices to radio-communicate with each other so as to acquire second radio communication information including a parameter obtained for each pair of the terminal and installed devices ; an characterised by nearby installed device detection means detecting from among the multiple installed devices , the installed device for which the parameter for that installed device in the first radio communication information is closed to the parameter in the second radio communication information by calculating an evaluation value representing the degree of equality between the parameter for that installed device in the first radio communication information and the parameter in the second communication information for each of the installed devices using a given formula whereby the parameter included in the first radio communication information and the parameter included in the second radio communication information are the same and represent either electric field intensity or propagation time. first radio communication information acquisition means requesting multiple installed devices installed within a given space (S) to radio-communicate with each other so as to acquire first radio communication information including-a parameter obtained for each pair of the installed devices for each of the installed devices ; first radio communication information storing means recording the first radio communication information acquired by the first radio communication information acquisition means for each of the installed devices ; second radio communication information acquisition means requesting a terminal to be located within the given space (S) and the multiple installed devices to radio-communicate with each other so as to acquire second radio communication information including a parameter obtained for each pair of the terminal and installed devices ; an characterised by nearby installed device detection means detecting from among the multiple installed devices , the installed device for which the parameter for that installed device in the first radio communication information is closed to the parameter in the second radio communication information by calculating an evaluation value representing the degree of equality between the parameter for that installed device in the first radio communication information and the parameter in the second communication information for each of the installed devices using a given formula whereby the parameter included in the first radio communication information and the parameter included in the second radio communication information are the same and represent either electric field intensity or propagation time. <EOS>