This research is to develop the Scale of Parental Belief in Involvement so as its reliability and validity based on parents' valuing learning and parental self-efficacy. 110 parents whose child studied in junior high school served as pilot run's samples. The pilot run's results of factor analysis revealed that three factors named parents' valuing academic learning, parents' valuing physical and musical learning as well as parental self-efficacy constituted the scale and explained 52.51% variance of parental belief in involvement. Internal consistency calculated by Cronbach's α was .87. The results of formal 444 parents were utilized to further validate the scale as well as its reliability and validity. Confirmatory factor analysis showed that the model was in goodness of fit which meant the selected items can be explained by the three latent factors properly. Applying the grade points average (GPA) and school performance rated by their teachers as the criterions, besides parents' valuing physical and musical learning, all factors were significantly correlated with both criterions, which were the evidences of criterions related validity. The Scale of Parental Belief in Involvement generated the solid evidences for both reliability and validity. Implications for educational guidance and future studies were discussed accordingly.