A wireless network system includes a user device, a client and an access point. In the wireless network system, a wireless network mode of the client is started in an AdHoc mode in response to specific operation, a wireless network mode of the user device is switched to an AdHoc mode when it is detected that the wireless network mode of the client is started in the AdHoc mode. Then, infrastructure network information including a network name and an encryption key for setting the wireless network communication in the infrastructure mode is transmitted from the user device to the client, and the wireless network mode of the client is switched to the infrastructure mode on the basis of the infrastructure network information.