A salt of a quinazoline derivative and a method for producing the same are provided. The present invention relates to a maleate of a compound represented by the following formula I, a process for producing the same, a pharmaceutical composition thereof, and a tumor thereof, for example, treatment of a plurality of malignant tumors such as non-small cell lung cancer and breast cancer. Regarding use. [Chemical 1] [Selected figure] None【課題】キナゾリン誘導体の塩およびその製造方法の提供。【解決手段】本発明は下記式Iで表される化合物のマレイン酸塩、その製造方法、その医薬組成物、およびその腫瘍、例えば非小細胞肺癌、乳癌等の複数種の悪性腫瘍の治療における使用に関する。[化1]【選択図】なし