An operation device includes an operation unit including an operation body worked by an operator's manipulation; a position detecting part detecting a position of the operation body; and a display unit displaying a position of the operation body. The display unit includes an operation member, a supporting body, and a movable load applying mechanism including a movable member, a magnetic generating mechanism, a magnetorheological fluid, and an operation controlling part. The display unit includes a display part displaying the operation position. A display controlling part PS controls a display. A controller is included to control the operation controlling part and the display controlling part. In a control method of the operation device, the controller controls to display a state of the operation position of the operation body on the display part.