A relay device includes a first session establishing portion to establish a first communication session with a cloud server located outside a firewall, a second session establishing portion to establish a second communication session with a control target device located inside the firewall, a device information acquiring portion to acquire device information about the control target device, and a relay portion to relay a communication between the cloud server and the control target device. The relay portion includes an executability determining portion to determine whether the control target device can execute a process specified by a control command received from the cloud server, a suspending portion to suspend an output of the control command when the determination result is non-executable, and a proxy transmission portion operable, when the determination result becomes executable after the control command was put on hold, to transmit the control command to the control target device.