This article presents the results of the adaptation and validation of the Attitudes Toward Trans Men and Women (ATTMW) scale—a measure capable of detecting transphobic positions towards trans men and women—in the Spanish context. A total of 310 prospective teachers from different stages of education participated in the study on its adaptation. In order to provide quantitative evidence of validity, confirmatory factor analysis and regression analysis with different constructs and sociodemographic variables were carried out. Internal consistency reliability was adequate. The study demonstrated that the ATTMW is a psychometrically sound instrument for the assessment of attitudes towards trans people, especially with items that categorize trans women and men as second-class people