PURPOSE: To control the entire body of an axial-flow pump device in an optimum condition by accurately detecting a suction force condition of the axial- flow pump, and by controlling the driving and stopping of the axial-flow pump, as well as the opening/closing of inlet/exhaust valves, and so on, based on the detected information.

CONSTITUTION: In a turbo-molecular pump 2 as an axial-flow pump, a pump load detector 5 is mounted. Based on a detection signal from the pump load detector 5, through a controller 6 of the turbo-molecular pump 2 as well as main controller 7 of an axial-flow pump device, a valve 1 on the suction force side and a valve 3 on the exhaust force side are controlled, respectively. When the ultra vacuum pressure exceeds, for example, a set value, the turbo-molecular pump 2 is temporarily stopped by the controller 6, and the valve 1 on the suction force side is closed. So as to meet the ultra vacuum condition controlled by the controller 6, a front stage pump 4 is controlled by the main controller 7.