A substrate storage tray that can be decreased in size for transportation. A substrate storage tray (1) for storing a large size substrate (20) includes a frame member (2) that includes a pair of first frame portions (5) opposed to each other and a pair of second frame portions (6) opposed to each other and has a frame shape, a substrate supporting member (3, 4) that has a plate shape, is disposed inside a region enclosed by the frame member (2), and is arranged to support one surface of the substrate (20), and extending portions (7) that are provided to middle portions in a long direction of the pair of first frame portions (5) and are arranged to widen a space between the pair of second frame portions (6).