A machining system includes: a cover body (131) having an opening (132) and defining a machining area (110) of a workpiece; a door portion (136) provided in the opening (132); an actuator (141) that operates the door portion (136) between a first position at which the opening (132) is closed and a second position at which the opening (132) is opened; a controller that controls the actuator (141); and a robot arm (212) that operates through the opening (132) to convey a workpiece between the machining area (110) and an external area outside the machining area (110). The controller controls the actuator (141) such that the door portion (136) is positioned at a third position when the robot arm (212) conveys the workpiece. An opening area of the opening (132) opened when the door portion (136) is positioned at the third position is smaller than an opening area of the opening (132) opened when the door portion (136) is positioned at the second position.