A method for replacing plural substrates to be processed by a substrate processing apparatus which includes a substrate processing chamber, a load lock chamber, and a conveying apparatus including first and second conveying members for conveying the plural substrates into and out from the substrate processing chamber and the load lock chamber. The method includes the steps of a) conveying a first substrate out from the substrate processing chamber with the first conveying member, b) conveying a second substrate into the substrate processing chamber with the second conveying member, c) conveying the second substrate out from the load lock chamber with the second conveying member, and d) conveying the first substrate into the load lock chamber with the first conveying member. The steps c) and d) are performed between step a) and step b).