The aim of the current study is to develop and validate an instrument to measure the four sources of teacher efficacy among Chinese primary school teachers. A 26‐item Sources of Teacher Efficacy Questionnaire (STEQ) was proposed with four subscales: mastery experience, vicarious experience, social persuasion, and physiological arousal. The results supported the hypothesized four‐factor structure of the STEQ. Scores from all the four factors of the STEQ had strong significant correlations with the Teachers’ Sense of Efficacy Scale (TSES), which showed the criterion‐related validity of the STEQ. Further, scores of all four sources significantly predicted teacher efficacy scores, among which social persuasion was the strongest predictor. This study contributes to the self‐efficacy literature by providing researchers with an instrument for examining the various facets of teacher efficacy. The findings can inform school principals and teacher educators, enabling them to facilitate a school culture and teaching environment that cultivates a greater sense of teacher efficacy and, in turn, better teaching performance.