This study examines the effectiveness of a simultaneous intervention in kindergarten and home to improve ball skills in children. Two kindergartens in Ibaraki, Japan, were divided into intervention (N = 98, mean age = 5.5 [0.6] years) and control groups (N = 88, mean age = 5.6 [0.6] years). The intervention was for 4 weeks. Parents received emails with video URLs for four ball activities once a week, and they undertook the activities introduced in the video at home with their children. Before the intervention, a 60-min workshop was held for kindergarten teachers. Ball skills (distance thrown and percentage of ball catches) were assessed pre- and postintervention. Two-way repeated measures analysis of variance and multiple regression analysis were used to compare the groups and explore the factors related to the improvement of ball skills. As a result, although throwing skills did not change significantly in both groups, there was an increase in the frequency of ball activity at home and perceived change of batting skills, both of which were associated with post-throwing skills. Catching skills improved significantly only in the intervention group; however, no significant factors related to the improvement of these skills were found. Our study demonstrates that simultaneous intervention in kindergarten and home may contribute to improve catching skills over a short period of time.