Substrate transport system and substrate position adjustment method

To improve throughput when transporting at least two substrates. Provided is a substrate transport system comprising: a transport means having a holding member that holds at least two substrates as a set parallel to a horizontal direction, the transport means transporting the held substrates from a transport source to a transport destination; a plurality of placement platforms that are provided to the transport destination, the substrates held by the holding means being respectively placed on the plurality of placement platforms at the transport destination; support members that are provided to the placement platforms and are capable of moving vertically relative to the placement platforms, the support members supporting the substrates once the substrates are partway through being placed on the placement platforms from the holding member, and separating the substrates from the holding member; and a plurality of movement means that respectively move the support members in an independent manner in the horizonta