The problems studied in the study relate to the low ability of students' mathematical problem solving as well as the use of less learning models that provide opportunities for developing mathematical problem solving skills. Therefore, the purpose of this research is to know the effect of Realistic Mathematics Education (RME) model on mathematical problem solving ability of grade VIII students of Semester Even SMP Negeri 1 Sendangagung Lesson Year 2017/2018. This research is using experimental method. The population in this study is all students of class VIII SMP Negeri 1 Sendangagung consisting of 5 classes with the number of 124 students, while the sample taken 2 classes of class VIII-5 as the experimental class and class VIII-4 as a class Control. To know the problem solving ability of mathematic student writer do test in essay form as much as 5 problem which first have been tested its validity and reliability. Hypothesis testing to determine the effect of RME using t test. From the results of hypothesis testing obtained t= 8.11 with a significant level of 5% known  = 2.01 means t> t  that is 8.11 > 2.01, so it can be concluded that "there is influence of learning model RME on the ability of problem solving mathematically grade VIII students even semester SMP Negeri 1 Sendangagung academic year 2017/2018 ". This situation is also seen from the average score of students' mathematical problem solving abilities in which the experimental class has an average value of 82.40 and the control class has an average value of 50.70.