Science teaching-anxiety and science teaching-efficacy are influential factors in teachers' teaching practices and behaviors. In order to encourage elementary teachers to do better teaching practice, this study identified factors that have caused teachers' science teaching-anxiety, developed an instrument measuring science teaching-anxiety, and investigated the relationship between science teaching-anxiety and science teaching-efficacy. In addition, we attempted to suggest practical implications to enhance teachers' confidence in science teaching. The guiding research questions were 1) which factors affect science teaching-anxiety level of the preservice elementary teachers, and 2) how each factor of science teaching-anxiety is related to science teaching-efficacy. The subjects were 133 Korean preservice elementary teachers (57.1% were female) in a large city. The data sources included teachers' responses to three paper and pencil questionnaires: State-Trait Anxiety Inventory (STAI), Science Teaching-Anxiety Questionnaire (STAQ), and Science Teaching Efficacy Belief Instrument (STEBI-B). To clarify the science teaching-anxiety, we specified it into six factors: trait anxiety about nature of science and science teaching, state anxiety about instruction, science activities, student assessment, and professional responsibilities. The results indicated three significant aspects of science teaching anxiety and efficacy. First, their level of anxiety about professional responsibility and science teaching was relatively high among six factors. Second, there was a negative correlation between science teaching-anxiety and science teaching-efficacy. Third, trait anxiety about science teaching is the most influential factor for science teaching-efficacy while state anxiety about instruction and professional responsibilities were followed.