A plate, a plate-holding apparatus, and a holding method for the plate for facilitating work to attach the plate to a plate-receiving metal frame of a sliding nozzle device. A gap is ensured between a to-be-held portion of the plate and an inner wall surface of an engagement groove such that, when the plate is held by engaging the to-be-held portion of the plate with the engagement groove of a holding portion of the plate-holding apparatus, the plate is movable in the longitudinal direction, the width direction, and the thickness direction of the plate.