Working memory capacities are associated with mathematical development. Many studies have tried to improve working memory abilities through training. Furthermore, the central executive has been shown to be the component of working memory, which is the most strongly related to numerical and arithmetical skills. Therefore, we developed a training program that specifically targeted the central executive to examine the possible impact on kindergarteners' working memory and numerical abilities. Thirty-four 5-6 year olds were randomly assigned to the experimental or the control conditions. Both groups received 16 30-minute sessions of their respective training program. The experimental group was trained with games tapping the central executive and the control group received a vocabulary-learning program. The results showed an immediate training effect on one central executive task and an effect of training appeared on another central executive task at follow-up, 6 months later. However, no impact was observed on numerical and arithmetical skills.