The invention provides a highly reliable plasma processing apparatus having stable sealing performance. The vacuum processing apparatus comprises a vacuum vessel having its inside decompressed; an opening disposed in a wall of the vacuum vessel for communicating the inside with the outside thereof and through which a sample to be processed is taken in and out; a valve body 701 disposed outside the wall for airtightly sealing or opening the opening; and a drive unit for driving the valve body to carry out the sealing or opening operation, the drive unit comprising a first member 705 coupled to an actuator 702 that moves along a substantially linear first direction as a result of operation of the actuator, a second member 706 coupled to the first member 705 that moves along a substantially linear second direction that intersects with the first direction, and the valve body 701 coupled to the second member that seals the opening as a result of the movement of the second member.