A substrate holder stocker device capable of reducing foot print is provided. The device includes: a movable table A which holds a plurality of substrate holders side by side in a plate thickness direction thereof and moves back and forth; a movable table B which is provided parallel to the movable table A and holds a plurality of the substrate holders side by side in a plate thickness direction thereof, and which moves back and forth; and an inter-table transfer mechanism for allowing the substrate holder which is held by one of the movable tables A and B stopped at predetermined positions to be held by the other of the movable tables A and B.