To reduce load on an access point even if a large number of wireless stations are located very close to the access point. An access point detects a communication load value (S1 and S2) and reports it to wireless stations (S3). The access point waits for a predetermined time after the transmission of the communication load value (5) and detects a communication load value again (S6 and S7). The access point determines whether the first communication load value is larger than a predetermined value K (S4) and whether the second communication load value is larger than K (S8). If the first and second communication load values are larger than K, the access point outputs a warning output command instructing the wireless stations to output a warning prompting their users to move away from their current locations (S9).