Researchers found that the teachers’ self-efficacy can help to promote the constructivist approaches of engaged teaching learning activities such as group works and better classroom management. However, few studies have focused particularly on examining science teachers’ self-efficacy on student engagement but not toward three dimensions of behavioral, cognitive and emotional engagement of learning. In this sense the major goal of this study was to develop a reliable, valid, and efficient questionnaire to assess science teacher’s self-efficacy towards three dimensions of student engagement. An instrument for measuring secondary school science teachers self –efficacy belief was developed and standardized. With this instrument a survey study on the level of self-efficacy of science teachers was performed with representative sample of 150 secondary school science teachers from community schools of Kathmandu and Lalitpur districts of Nepal . The level of efficacy on each constructs across all demographic variables except ethnicity was found to be moderately high. Dalit teachers’ efficacy level on behavioral engagement of student was found to be moderate. Significant relationships were not established between self-efficacy and any demographic variables, such as gender, age, experience, qualification, and ethnicity. The discussions of the findings were based on Bandura's Social Cognitive Theory.