The focus of this study was to identify the improvement of students' spatial ability as an impact of realistic mathematics education approach. This study was an experimental research, involving the eighth grade students of the good level and middle level schools. The sample of this study consisted of 152 students. The instruments used in this study were the spatial ability test. The data were analyzed by using Mann-Whitney U test, t-test, r correlative analysis, 1-way and 2-way ANOVA with the post hoc test. Based on the result of the data analysis it can be concluded that the students' spatial ability under Realistic Mathematics Education approach was better than that of the students taught using the conventional approach. There was an interaction between the instructional approach and the school level toward the enhancement of students' spatial ability.