ABSTRACT They aims of this study is to know whether  there is a significant influence of applying contextual   learning on student’s mathematical problem  solving ability at the eleventh grade student’s of  MAN Barumun Tengah. This research was contucted by applying experimental (one group pre test post test design) with 30 student’s and they were taken  by using random sampling  technique from 144 student’s. Observation and test were used in collecting  they data. Based on descriptive analysis,  it was found that : (a)  the average of applying contextual learning was 3,5 ( very good category) and (b) the average  of student’s  mathematical problem solving ability before of applying contextual learning was 46.66 ( fair category) and after using of applying contextual learning was 71,2(good category). Furthermore, based on inferential statistic by using pair sample t  tes SPSS version 16, it could found significant value was tess 0.05 (0.000<0.05). It means, there is they influence of applying contextual learning on student’s mathematical problem solving ability at the eleventh grade student’s of MAN Barumun Tengah. Keyword  : applying contextual learning, student’s mathematical problem solving