The purpose of this study is to analyze how pre-service teachers perceive mathematics problems by making good mathematics problems at the elementary school level and applying them to elementary school students. In this study, 86 pre-service teachers enrolled in the second and third grades of A University of Education presented good mathematics problems they thought of. In addition, these pre-service teachers predicted the solution strategies of elementary school students for the proposed mathematics problem and described the teacher's expertise while observing the problem-solving process of elementary school students. As a result of the study, pre-service teachers preferred mathematical problems needed for using mathematical concepts or algorithms, motivation, and open-ended problems as good mathematics problems, and thought that students' in-depth observation and analysis experiences could help improve teachers' problem-solving expertise. In order to enhance teachers' expertise in solving mathematics problems, the researcher proposed for pre-service teachers to observe students' mathematics problem-solving processes, to experience in developing high-quality mathematics problems, and also to distribute high-quality mathematics problems linked to textbook problems.