A parameter control device includes a parameter updating unit, and an operational screen displaying unit. In a case where any one of the individually operated portions is operated, the parameter updating unit changes the parameter of the controlled device, which is associated with the relevant individually operated portion, by following an operation amount of the individually operated portion. In a case where a cooperative operated portion is operated, the respective parameters of the plurality of controlled devices are changed by following an operation amount of the cooperative operated portion. The operational screen displaying unit displays the respective parameters of the plurality of controlled devices, displays the plurality of operated portions in positions corresponding to displays of the parameters of the respectively associated controlled devices, and displays the cooperative operated portion in a position corresponding to a display of a parameter of the master device.