This research is motivated by the ability of adaptive reasoning of students who are still low. To overcome these problems, researchers use Realistic Mathematics Education because this learning stage supports the indicators of Adaptive Reasoning ability of students. The purpose of this research is to know the improvement and achievement of Adaptive Reasoning ability of students through learning approach of RME. The method used in this research is the quasi experiments with the nonequivalent design study of pretest-posttest control group design. The population in this research is all students of class IX SMP Negeri 5 Kota Tasikmalaya Lesson Year 2015/2016. Sampling in this research is done by purposive sampling with class IXF as experiment class that is learning of RME and class IXG as control class that is conventional which each consist of 32 students. Technique of collecting data that is using test instrument in the form of description is 4 problems. Data analysis techniques used to test the hypothesis are t test and Mann-Whitney test with significance level of 5%. Based on the results of research, data processing, data analysis and hypothesis testing, it is concluded that the increase of adaptive reasoning of (upper and middle) PS category students who gain RME learning is better than students who get conventional learning. Keyword: Realistic Mathematics Education, Adaptive Reasoning.