A processing apparatus includes a substrate supporting unit that supports a substrate in a processing space in which the substrate is processed, a first partitioning member that includes a ceiling portion having an opening and partitions the processing space from an outer space, and a second partitioning member that is attached to the first partitioning member so as to close the opening and partition the processing space from the outer space together with the first partitioning member. The second partitioning member is attached to the first partitioning member so that the second partitioning member is removable from the first partitioning member by moving the second partitioning member toward a space which a lower surface of the ceiling portion faces.