The aim of the study was to adjust the measurement model of an instrument of sources of Self-efficacy for Mathematics to sample of university students from Northeast of Mexico and the sex measurement invariance. A second-order modeling was performed, which shows convergent and discriminant validity, which corresponds to the original Bandura theory of self-efficacy and contains four factors: experience in mastery, social persuasion, vicarious learning, and physiological state (emotional activation). There was adequate goodness of fit of the model in the confirmatory analysis. The advantages of the use of this instrument are discussed for its simplicity and ease of applications, qualification, and interpretation, to be used by teachers, tutors, and advisors of mathematics.