An image processing system includes: an application server installed on a network; an image processing device installed on a local network connected to the network; a relay server, installed on the local network, that relays communication between the image processing device and the application server; and a connection mediation server, installed on the network, that transmits a connection request to the relay server to cause the relay server to connect to the application server. The connection mediation server includes a request accepting circuit, and a connection request circuit, the relay server includes a connection establishment circuit, and in a case where a communication request is accepted, the connection request circuit transmits the connection request to the relay server, and in a case where a new communication request is accepted, the connection request circuit does not transmit the connection request to the relay server.