A printing apparatus, comprising a conveyance unit for conveying a sheet, a carriage mounted with a printhead and configured to scan the printhead in a sheet widthwise direction, a platen arranged so as to face the printhead, a detection unit mounted on the carriage and configured to detect a distance to a sheet, a support portion, for supporting a sheet from below, arranged on a downstream side of the carriage in a conveyance direction, movable between a first position at which the support portion forms a conveyance surface for a sheet and a second position at which the support portion protrudes above the conveyance surface, and a determination unit configured to determine, based on a detection result of the detection unit, whether the support portion is at the first position or the second position.