The purpose of this study was to investigate the effects of game-based-digital textbook on the basic arithmetic abilities and the task attention of students with mental retardation. To do this, 38 students with mental retardation participated and were assigned to the three groups. The first group only used the traditional text book, the second group only used the game-based-digital textbook, and the third group used both the traditional textbook and the game-based-digital textbook. The third group using both the traditional textbook and the game-based-digital textbook revealed more higher improvement than the other two groups in the basic arithmetic and the task attention.