PURPOSE: To achieve vacuum and shorter a vacuum dissolving time by providing (O) rings at two positions of a sample holder so that a spare exhaust room is formed with one (O) ring and the high vacuum portion in a scope cylinder is sealed from the spare exhaust room with the other (O) ring.

CONSTITUTION: In a valve-closed state, the inside of a scope cylinder, separated from a spare exhaust room, is kept in a high-vacuum state, however during the motion of entering a sample holder into the scope cylinder the valve is open, and so the inside of the scope cylinder communication with the spare exhaust room and an (O) ring 13 moves while sealing the inside cylinder of a goniometer, and when the holder is deeply inserted an (O) ring 51 is entered into the tip portion of the inside cylinder of the goniometer and engaged with the inner face of a cylinder portion 53 to begin vacuum-sealing. At this time, the spare exhaust room of the goniometer is separated from the vacuum of the scope cylinder. The load of a pump for an electron microscope itself operates only on the portion ahead of the (O) ring 51, then allowing a high vacuum state to be achieved easily.