This paper presents an optimal management model for structural and operational optimization of an integrated district heating system (DHS) with multiple regional branches. A DHS consists of energy suppliers and consumers, district heating pipelines and heat storage facilities in a region. The integrated DHS considered in this paper consists of 11 regional DHS branches. In the optimal management system, production and consumption of heat, transport and storage of heat at each regional DHS are taken into account. The optimal management system is formulated as a mixed integer linear programming (MILP), where the objective is to minimize the overall cost or to maximize the profits of the integrated DHS by generating electricity while satisfying the operation constraints of heat units and networks, as well as fulfilling heating demands from consumers. Evaluation of the operation cost is based on daily operations for two months (during August and December) at each DHS located in Seoul and Gyeonggi-do in Korea. Results of numerical simulations show the increase of energy efficiency due to the introduction of the present optimal operation system.