Reasoning skills assumes a significant part in fostering any remaining numerical abilities. Numerical thinking capacity is one of the numerical capacities that should be developed in school learning. Beside cognitive perspective, one of the affective viewpoints is self-efficacy, which is helpful for learners in mathematics learning. Students must be confident in their ability to solve these difficulties. As a result, the goal of this study was to see if there was a relationship between sources of self-efficacy and mathematical reasoning ability among grade 10 students. The study used descriptive-correlational research design which was conducted during the school year 2020-2021, with forty-one (41) grade 10 junior high school students. The study utilized adapted-modified survey questionnaire and researcher-made examination. The result of the study revealed that there is a significant relationship between sources of self-efficacy in vicarious experience and mathematical reasoning ability in terms of mathematical connection and logical thinking. The next researcher may increase the number of respondents, according to the findings. This may upgrade the precision and legitimacy of gathered information and dependability of the outcomes.