In the present positioning apparatus, a positioning apparatus, comprising: a box body including a process chamber exposed to a decompression environment in the interior of the box body and an opening allowing said process chamber to communicate with an outside; a moving member for shielding said opening of said box body with a slight clearance between said box body and the moving member and movable with respect to said opening of said box body; and a differential pumping seal for sealing said slight clearance between said opening of said box body and said moving member, wherein a portion of said moving member to be moved into the interior of said process chamber, when said moving member moves, is formed as an adsorption preventive area.