A machining system includes a cover body having an opening and defining a machining area of a workpiece, a door portion provided in the opening, an actuator that operates the door portion between a first position at which the opening is closed and a second position at which the opening is opened, a controller that controls the actuator, and a robot arm that operates through the opening to convey a workpiece between the machining area and an external area outside the machining area. The controller controls the actuator such that the door portion is positioned at a third position when the robot arm conveys the workpiece. An opening area of the opening when the door portion is positioned at the third position is smaller than an opening area of the opening when the door portion is positioned at the second position.