To provide a substrate processing device allowing easy maintenance of a processing part and capable of preventing application of excessive moment load to a base and a slide mechanism.

A processing chamber 3 is placed on a sliding unit 5 slidable relative to a processing part cover 2 along a sliding direction L and can be drawn out in front of the processing part cover 2 via the open front face 21 of the processing part cover 2. The processing chamber 3 can also be drawn out toward a conveying robot 4 via the rear face 22 of the processing part cover 2. Therefore, since the processing chamber 3 can be drawn out to each side of the processing part cover 2, all the parts of the processing chamber 3 are within easy reach. Since the entire processing chamber 3 does not need to be drawn out toward one side of the processing part cover 2, the center of gravity of the entire device is not greatly biased to the side to which the processing chamber 3 is drawn out.