A 2‐year longitudinal study of 33 children aged 4–6 years was conducted to clarify the developmental relationship between calculation skill and finger dexterity, as well as the selectivity of the predictive power of finger dexterity on later calculation skill. We examined individual developmental change in the relationship between addition performance and finger dexterity and observed whether children fit a linear developmental pattern. Multiple regression analysis showed that participants' performance on addition tests was strongly predicted by their finger dexterity. However, their performance on vocabulary tests was not strongly influenced by finger dexterity. These findings suggest that calculation skill in children aged 4–6 years is strongly related to finger dexterity.