The present invention is related to a method for transferring substrates. The method comprise simultaneously transferring two substrates, by means of a transfer unit, between first support plates disposed to be vertically spaced apart from each other and second support plates arranged abreast in a lateral direction. The transfer unit comprises a top blade and a bottom blade converted to a folded state where they are vertically disposed to face each other and an unfolded state where they rotate at a preset angle in opposite directions. The transfer unit place/take a substrate on/out of the first support plates under the folded state and place/take a substrate on/out of the second support plates under the unfolded state.