To better understand the issue of mathematical learning difficulties, it is necessary to analyze the fundamental structures and processes that influence various mathematical performances. In this context, working memory serves as the foundational structure for knowledge acquisition. A look at the current state of research reflects clear correlations between mathematical skills and working memory performance. However, there are few studies that investigate the preschool age. This paper aims to fill this gap. Based on a sample of 249 children (ages 4-6), a working memory test and a math test are developed. Furthermore, the influence of the working memory components according to Baddeley on different areas of mathematical skills is examined. The results demonstrate an influence of the individual components of working memory on mathematical performance, which in turn reflects the developmental stage of mathematical skills. In this regard, the central executive's processing capacity primarily supports newly acquired mathematical skills. In contrast, automated mathematical processes are predicted by the subsystems, mainly by the phonological loop and by resource-saving central executive capacities.