A connection method of a communication device in a communication system is provided. The communication system includes a plurality of communication devices each having a wireless LAN (Local Area Network) access point function and a wireless LAN child device function and is constructed by connecting a lower-level communication device to an access point of a higher-level communication device. A new communication device is to be added to the communication system executes: a first step of connecting to an access point of an arbitrary one of the plurality of communication devices of the communication system; and a second step of acquiring, from the connected communication device, system information of the communication system including a connection form of the plurality of communication devices.