This study aims to find out: 1) Is the increase in mathematical communication skills of students who are given learning using the Ethnomathematics-based RME (Realistic Mathematical Education) approach better than those given conventional learning; 2) Is the increased self-confidence of students who are given Ethno-mathematics based RME (Realistic Mathematics Education) learning better than those given conventional learning. This research is a quantitative research that is experimental in nature. The data collection technique used a test of students' mathematical communication skills which totaled 4 items of description in accordance with the indicators of students' mathematical communication abilities and filled in the student's self-confidence questionnaire which totaled 14 statements which consisted of 7 positive statements and 7 negative statements. And the data analysis technique used was the normality test, the Mann Whitney u test and the N-Gain test. In which the researchers took random samples, namely class VII C as the experimental class and class VII B as the control class at SMP Negeri 3 Kragilan. The results of the study showed that the increase in mathematical communication skills and students' self-confidence given the Ethnomathematics-based Realistic Mathematical Learning approach was better than the class given conventional learning. Keywords; students' mathematical communication skills, student self-confidence, RME (Realistic Mathematical Education) approach, Ethnomatematics