This study constructed a marine science affect scale to understand junior high school students’ emotions toward the ocean. This work comprised three stages. First, the researcher compiled factors and items associated with marine perception through an extensive literature review. Second, the compiled factors, the items of each factor, and their content validity were examined by eight experts, and a scale was constructed containing 7 items with 2 factors. Third, this was tested on a sample of 1,683 Taiwanese junior high students. The results from a series of multigroup confirmatory factor analyses supported the reliability, content and construct validity, and gender invariance of the questionnaire.