First, if the information server 500 has received collected data on IoT devices 100 from the mobile terminal 300 (step S961: Yes), the information server 500 extracts the number of surrounding IoT devices 100 written in the collected data (step S962). Then, in a case where device information exists (step S963: Yes), the following registration process in and after step S964 is performed.

That is, attribute information and the like on the IoT devices 100 are extracted (step S964). Information on times at which signals have been received from the IoT devices 100 is extracted (step S965).

Here, if arrangement positions of the IoT devices 100 have been written (step S966: Yes), the arrangement positions of the IoT devices 100 are extracted (step S967), and parameters of the IoT devices 100 are registered in the database (step S976).

On the other hand, if arrangement positions are not written (step S966: No), information on strengths of received electric fields received at the mobile terminal 300 is extracted (step S971). Then, if a new IoT device 100 exists (step S972: Yes), a position where the IoT device 100 exists is inferred by calculation (step S973). Parameters of these IoT devices 100 are registered in the database (step S976).

If a new IoT device 100 does not exist (step S972: No), information on an existing IoT device 100 that has been registered in the database is obtained (step S974). Then, a position where the IoT device 100 exists is inferred by calculation again (step S975). Parameters of these IoT devices 100 are registered in the database (step S976).