Science is comprised of theory and practical work and to study either part is not enough to understand the whole. Practical work such as observation and fieldtrips should be used to develop students' inquiry skills as well as to support the theory. Teachers with high self-efficacy on fieldtrips will be more likely to use this technique. Self-efficacy can be described as the perception of individual capacity. When the teacher candidates and teachers are considered, self-efficacy beliefs affect teachers' classroom practices and teachers with a high self-efficacy level are more passionate about teaching. This study intended to construct a self-efficacy scale for pre-service science teachers on field-trips. The study also aimed to determine whether these beliefs vary by gender, class, secondary school type, whether the fieldtrip was used in high school and university courses. Survey design was used in this study and the population was determined as all science education students at Turkish universities. The sample consisted of all 265 students at Nigde Ömer Halisdemir University. Data were collected by administering the "Self-Efficacy Beliefs on Fieldtrip Scale" by Öztürk (2008) to 249 pre-service science teachers. The students' responses were analysed in order to construct a self-efficacy scale. Item and scale analyses were done to assess the reliability of the scale and validity of the scores. Nonparametric tests were used to determine whether the beliefs differ according to those factors. Results showed that self-efficacy beliefs are multidimensional (consisted of task efficacy, coping with problems efficacy, teaching efficacy, and pre-visit actions efficacy); and pre-service teachers' beliefs were positive except coping with problems efficacy. The results also revealed that efficacy beliefs of the pre-service science teachers differed with gender (for pre-visit actions efficacy girls had higher scores than boys), the class level (pre-service teachers at lower grades had high efficacy on pre-visit and task efficacy compared to those at higher grades), and whether fieldtrips were used in high school (for task efficacy pre-service teachers whose high school courses were taught with fieldtrips had higher scores than those whose high school courses were not taught with fieldtrips). On the other hand no significant differences were found among pre-service teachers on class level, secondary school type, and whether fieldtrips were used in university courses.