The relationship between the gross national product (GNP) and amount of groundwater abstraction in the wards of Tokyo before the regulations on groundwater pumping came into effect was investigated to facilitate estimation of the amount of groundwater abstraction in the past. The relationship was approximated using a piecewise linear function with the folding point at around 1959. The estimated groundwater abstraction rate from the relationship obtained was consistent with temporal changes in the land subsidence rate observed and the hydraulic head corresponding to the Great Depression or World War II. The proposed methodology is expected to be applicable to similar estimations in Asian megacities, which are now undergoing rapid national economic growth.