Academic interest constitutes a variable that affects the learning process of students. However, no instruments have been found that measure the interest of university students in the Spanish context. Therefore, the objective of this study was to adapt and validate the Student Interest Scale (Mazer, 2012) into Spanish. Four hundred and forty-seven students from the Early Childhood and Primary Education Degrees at the University of Cádiz participated in the research. The results of the confirmatory factor analysis support both the bifactor structure proposed in the original model and the unifactor solution. Likewise, the scale presents adequate reliability by obtaining satisfactory values of Cronbach’s alpha and McDonald’s omega and evidence of convergent validity with motivation and academic satisfaction. It is concluded that the Student Interest Scale presents adequate psychometric properties to evaluate the academic interest of university students in the classroom.