Marseille, the typical sea-port city of Mediterranean France, was the most representative port of French Colonial Empire in the 19th century. Studying on Marseille of that time would contribute to the typological understandings of the sea-port cities in the period of Imperialism. This article aims to present a type of development which a sea-port city of the colonial empire could take, by interrogating the changes of harbors’ functions and the urban structure of Marseille in 19th century. The consequent findings are as follows. First, the population of Marseille had sharply risen from 1830 on, and increased three times from 1820 to 1870s. This increase of population marked the economic growth of the city. Carrying capacity of vessels entering the port of Marseille rising five times in 1825-1870 shows the scale and the process of this growth. However, this economic growth had attributed to the colonial expansion of France launched from 1830 on. Second, according to the rising traffic of port, the harbors of Marseille had been expanded to the north of old port(Vieux-Port) since 1840s. With their expansion, the harbors’ functions of Marseille had changed simultaneously, adding the industrial function to the traffic and distributive functions. Second, the industrialisation of Marseille also occurred in association with these circumstances. As a result, new and factory industries, such as sugar refining, oily industry, soap industry, machinery manufacture and foundering, etc. were thriving in the city and its suburbs. However, the material sources of these industries were from the French colonies, and, thus, the industrialisation was highly dependent on the supply from colonies. This is a remarkable feature of the Marseille’s industrialisation, and it can be that this industrialistation was a type of development which the sea-port city of the colonialist Empire would take. Third, the changes of harbor’s functions and the industrialisation had caused the transformation of urban structure of Marseille. Most notable transformation was the extension of city scale. Also, the appearance and shape of city had changed geometrically and orderly with the constructions of the various official buildings and monuments through the French Second Empire. Fourth, withstanding the extensions and changes of urban structure, the social character of neighborhood did not change so much at same time. Unlike with Paris where the neighborhood had been divided sharply between the bourgeoisie and the working-classes as a result of Haussmanisation, Marseille witnessed the loose line of division between the higher and lower classes, except with the ‘old city’ in the north of old port and the higher classes’ neighborhood in the southeast of it. However, one another consideration of social character was the reduction of proportion of natives in the neighborhoods. Throughout the mid-century, numerous immigrants fluxed into Marseille as the skill and unskill workers, and they gradually spread into all of the neighborhoods in the city. (Korea Maritime University, nykim@hhu.ac.kr/varlin@hanmail.net)