This historico-geographical study aims at the clarification of regional formation processes in modern Japan, based on the framework of interdependence between human agency and social structure in the structuration theory by Giddens. The biographical approach by Pred, that is the good method to appreciate the practices of human agency, is applied to a case study of Nagasaki City in the modern period. As the result of this consideration, it is confirmed that the duality of structure and the duality of structure and agency appeared in the lifetime and personal-spatial history of the powerful figures in this city, who were merchant, banker and statesman etc..