This study aims to analyze students' mathematical critical thinking skills based on self-efficacy and gender. This research is a qualitative descriptive study using research subjects from class X students of SMK Cendekia Batujajar. Purposive sampling technique was used to analyze the mathematical critical thinking skills of 6 subjects in each gender category (male and female). The instruments used in this study were tests of mathematical critical thinking skills, self-efficacy questionnaires, and interview guidelines. The data analysis used is data reduction, categorization and synthesis, as well as working hypotheses/conclusions. The conclusion of this study is that male students in the high self-efficacy category are better than male students in the medium and low self-efficacy categories. There are 4 indicators that have been fulfilled for male students in the high self-efficacy category, namely indicators of interpretation, analysis, evaluation, and inference. Meanwhile, male students in the medium self-efficacy category had fulfilled 1 TKBK indicator, namely the evaluation indicator and male students in the low self-efficacy category fulfilled 3 TKBK indicators, namely interpretation, evaluation, and inference indicators. In addition, female students in the high and medium self-efficacy categories did not fulfill all TKBK indicators and female students in the low self-efficacy category fulfilled 1 TKBK indicator.