Abstract: A substrate processing system includes: a carry-in/out section in which a cassette accommodating a plurality of substrates is carried in/out; a batch processing section in which a wafer lot including the plurality of substrates is collectively processed in a state where each of the plurality of substrates stand upright; a single-wafer processing section in which the plurality of substrates included in the wafer lot are processed one by one in a horizontal state; and an interface section that delivers the plurality of substrates from the batch processing section to the single-wafer processing section. The interface section includes: a standby table that horizontally holds a substrate in a state of being in contact with pure water; and a transfer mechanism that delivers the substrate from the batch processing section to the standby table.