Abstract: A substrate transport robot incorporated in a substrate processing apparatus includes a pair of retaining columns (35R, 35L) permitted to rotate on respective shafts (34) by a main body portion of the substrate transport robot. The side surface of each of the retaining columns (35R, 35L) is divided into five areas (AR1, AR2, AR3, AR4, AR5) in a circumferential direction about the axis of each retaining column (35R, 35L), and grooves (351A, 351B, 351C) for holding substrates are formed in the areas. Among these areas, an unprocessed substrate retaining area (AR4) holds substrates which have not yet been processed, an in-processing substrate retaining area (AR3) holds substrates with a cleaning liquid deposited thereon which are being processed, and a processed substrate retaining area (AR5) holds processed substrates which have already been subjected to cleaning processing and drying processing.