A substrate processing apparatus includes a transfer block, a processing block, and a buffering unit. The transfer block includes a bulk transporting mechanism that stores substrates into a carrier, and a first orientation converting mechanism that converts the substrates into a vertical orientation. The processing block includes a batch processing area, a single-wafer processing area, a single-wafer transporting area, and a batch substrate transporting area. In the batch processing area, batch processing baths and a second orientation converting mechanism for converting the substrates into a horizontal orientation are provided. In the single-wafer processing area, for example, a single-wafer processing chamber is provided. In the single-wafer transporting area, a center robot-ER is provided. In the batch substrate transporting area, a first transporting mechanism is provided. The bulk transporting mechanism-HER transports the substrates to the first orientation converting mechanism IS, and transports the substrates from the buffering unit.