A vacuum processing apparatus that includes a vacuum vessel; an opening disposed in a wall of the vacuum vessel, through which a sample to be processed is taken in and out; a valve body disposed outside the wall for airtightly sealing the opening; and a drive unit driving the valve body to carry out a sealing or opening operation. The drive unit includes a first member coupled to an actuator that moves along a substantially linear first direction as a result of operation of the actuator, and a second member coupled to the first member that moves along a substantially linear second direction that intersects with the first direction. The valve body, coupled to the second member, seals the opening as a result of movement of the second member.