The present invention is used for separating a superposed substrate in which a processing target substrate and a supporting substrate are joined together with an adhesive into the processing target substrate and the supporting substrate, and includes: a separation processing station performing predetermined processing on the processing target substrate, the supporting substrate, and the superposed substrate; a transfer-in/out station transferring the substrates into/from the separation processing station; and a transfer unit transferring the substrates between the separation processing station and the transfer-in/out station, wherein the separation processing station includes: a separation unit separating the superposed substrate into the processing target substrate and the supporting substrate; a first cleaning unit cleaning the processing target substrate separated in the separation unit; and a second cleaning unit cleaning the supporting substrate separated in the separation unit.