An embodiment provides a chemical strengthening system, including: a strengthening part in which chemical strengthening of a glass plate is performed; a heating part in which a post-heat treatment of the glass plate is performed; and a cassette in which the glass plate is loaded and which is movable between the strengthening part and the heating part. The cassette includes a lower support which supports a lower end portion of the glass plate, the lower support is rotatable with respect to an axis of rotation, and the axis of rotation does not move relatively within the cassette.