A storage unit of an embodiment includes a container, a rectifying plate, and an exhaust duct. The container provides a first space for storing a plurality of substrates therein, and a second space behind the first space. The rectifying plate is provided between the first and second spaces. The exhaust duct communicates with the second space. The rectifying plate has an effective region facing the first space. The effective region includes a first region and a second region. The first region faces a center of the first space. The second region extends on one side or both sides of the first region. In the first region, a plurality of through holes are formed to be distributed over the first region. The second region has a conductance lower than a conductance of the first region.