An operation terminal 1 is configured so as to transmit, as a control command, an individual control command transmitted individually to a specific control device 2 of control devices 2, or a collective control command broadcasted collectively to two or more control devices 2 of control devices 2. Control terminal 2 comprises: a command determination unit 2d determining whether received control command is individual control command or collective control command; and an information processing unit 2b which, if received control command is individual control command, responds by collectively broadcasting to a plurality of operation terminals a state change notification corresponding to execution of individual control command, and, if received control command is collective control command, responds by collectively broadcasting to operation terminals 1, with a timing different from the other control terminals 2, a state change notification corresponding to execution of collective control command.