The present invention provides a vacuum container, capable of keeping a sufficient mechanical strength and implementing a lightweighting, and reducing a material cost and a processing cost to the utmost. A plasma processing container (100a) includes a square tubular lower container (1) and an upper container (10) combining with the lower container (1). The upper container (10) has a frame (21), aspray head (25) connected to the frame through an insulating member (23), and a beam structure (27) arranged above the frame (21) and the spray head (25); a bottom board (31) composing the spray head(25) is exposed in an external space of the atmosphere pressure.