PURPOSE: To reduce the size of a whole apparatus by welding a metallic gasket flange for vacuum sealing in a wall of a sample chamber in a state recessed from an outer surface of the wall.

CONSTITUTION: A sample 2 is placed on a table 3 supported by a guide 4 to be movable in the direction of movement at the inside of a vacuum sample chamber 1. The table 3 in the vacuum is driven from the outside of the sample chamber 1 with a straight-line introducing machine 7 or the like. And a metallic gasket flange 5 for vacuum sealing is welded in a state recessed from the outer surface of the sample chamber 1 and is vacuum sealed with a gasket 6.