By a first transport robot, n substrates are unloaded from a first retaining portion, then simultaneously transported, and respectively loaded into n substrate holders consecutively arranged from one side defined with respect to an arrangement direction. Thereafter, a rotation mechanism rotates n+m substrate holders so as to perform a substrate inverting operation and so as to arrange the n+m substrate holders along the arrangement direction in an arrangement sequence reverse to a pre-rotation arrangement sequence. Thereafter, the n substrates loaded into the n substrate holders are unloaded in a group of m in a sequence from the one side, and loaded into a second retaining unit by a second transport robot. After the substrate inverting operation, n substrates are unloaded from the first retaining unit, and loaded again into n substrate holders consecutively arranged from the one side by the first transport robot.