The purpose of this study was to clarify the relationship between quality of motion and motor ability in early childhood, as well as the moderating effects of grade and gender. A total of 133 preschoolers (3- to 5-year-old class) were evaluated for quality of motion and motor ability using the “Athletic Aptitude Test II” developed by the Japan Sports Association to assess the fundamental movements of running, jumping, and throwing. Two observers evaluated quality of motion based on movies taken by tablet. The relationship between quality of motion and motor ability was determined using multiple regression analysis. In addition, we clarified the influence of grade and gender on the relationship between quality of motor and motor ability using moderation analysis. A significant relationship was found between quality of motion and motor ability for all movements. Grade moderated the relationship between the quality of running motion and the results of the 25-m run. Gender moderated the relationship between the quality of the throwing motion and the results of softball throwing. These results suggest an association between quality of motion and motor ability in early childhood, and show that improving quality of motion improves motor ability.