In this paper, we survey the thought of students for the reason of the study of mathematics, for mathematics, for the textbook of mathematics and the attitude appling mathematical knowledge in the real life and analyze that. We have a correct understanding how to study mathematics and that motivates study of mathematics to students. Student have a correct understanding how to use basic knowledge of mathematical theory in the real life and have for the study of mathematics. In this article, we investigate the reason for studying mathematics in the real life and analyze the way how to use basic knowledge of mathematical theories through actual examples. The reasons for studying math are divided into 3 categories: mathematics for obtaining common sense and wisdom, practical mathematics for application, and mathematics as a liberal art for promoting our characters and recreation. We investigate the reasons for studying mathematics in each category. By theses results, we make the effectual educational method for mathematics and investigate the effect.