To enhance the yield of a vacuum process by protecting a workpiece from contamination with undesired gas in a vacuum conveyance chamber.

In a platform PH, a vacuum transfer robot 16 has a base which performs slide operation, an arm drive 42 which is attached turnably onto the base in order to drive conveyance arms 12 and 14, and a box 44 in which the arm drive 42 and the drive conveyance arms 12 and 14 are housed. The vacuum transfer robot can slide on a guide rail 32 by straight driving of a ball screw mechanism 34. The window of a gas filter 52 is fixed to the sidewall of the box 44, an opening 48 through which the conveyance arms 12 and 14 can pass while holding a semiconductor wafer W during telescopic motion is formed, and a door 50 for opening and closing the opening 48 is fixed.