A CPU 51 detects the amount of flotation of a document pressing portion 38 (S11) once printing processing starts, and then sets a correction coefficient that a correction unit 61 for decision making uses according to the amount of flotation of the document pressing portion 38 (S12). CPU51は、印刷処理を開始すると、まず原稿押さえ部38の浮き量を検出し(S11)、続いて、原稿押さえ部38の浮き量に応じて判定用補正部61が用いる補正係数の設定を行う(S12)。 - 特許庁