The purpose of this study was to develop a questionnaire that measures students' motivation toward science learning (SMTSL). Six scales were developed: self-efficacy, active learning strategies, science learning value, performance goal, achievement goal, and learning environment stimulation. In total, 1407 junior high school students from central Taiwan, varying in grades, sex, and achievements, were selected by stratified random sampling to respond to the questionnaire. The Cronbach alpha for the entire questionnaire was 0.89; for each scale, alpha ranged from 0.70 to 0.89. There were significant correlations (p is less than 0.01) of the SMTSL questionnaire with students' science attitudes (r = 0.41), and with the science achievement test in previous and current semesters (r [superscript p] = 0.40 and r [superscript c] = 0.41). High motivators and low motivators showed a significant difference (p is less than 0.01) on their SMTSL scores. Findings of the study confirmed the validity and reliability of the SMTSL questionnaire. Implications for using the SMTSL questionnaire in research and in class are discussed in the paper.