INFORMATION PROCESSING SYSTEM

There is provided an information processing system including a relative-position estimation processing unit configured to estimate a relative position between an access point and a wireless client by using a cooperative position estimation method using distance information based on a signal strength between the access point and the wireless client; and an inside/outside determination processing unit configured to determine an inside/outside positional relationship between a polygonal target area formed by access points and the wireless client, in which the inside/outside determination processing unit determines whether the wireless client is present inside or outside the target area by determining a direction of vector product of the access points forming a side of the target area and a direction of vector product of the wireless client and the access point as a vertex of the polygonal area.