To provide a processing device capable of preventing a suction error between a substrate and a suction pad.

The processing device includes: a processing unit for performing prescribed processing on the substrate to be processed; and a conveyance stage for mounting the substrate and carrying the substrate. The conveyance stage includes a top face having an end portion vertically positioned lower than a center portion, when looked along a conveyance direction to carry the substrate. The conveyance stage further includes: support means for supporting the substrate disposed above the top face directly or indirectly; a retention member for movably retaining the substrate along a conveyance axis extending in parallel to the conveyance direction; and a drive unit for moving the retention member along the conveyance axis. The support height of the support means supporting the substrate is identical to the retention height of the retention member retaining the substrate in a processing unit installation area in which the processing unit is provided, and is lower than the retention height in an area other than the processing unit installation area.