An image forming system comprises: an application server installed on an internet; multiple image forming devices installed on a local network; multiple relay servers, installed on the local network, relaying communication between at least one of the multiple image forming devices and the application server; and a connection mediation server, installed on the internet, sending an access request to one of the multiple relay servers, and connecting the relay server to the application server. The connection mediation server includes: a relay server identifying part configured to identify the relay server which relays the communication between one of the multiple image forming devices and the application server from among the multiple relay servers; and an access request sending part configured to send the access request to the relay server identified by the relay server identifying part, and establish the communication between the image forming device and the application server.