The purpose of th research is to propose the hierarchical spatial cluster method for the efficient exploration of economic clusters in the urban spatial structures, and to testify it by the case study. The economic clusters making the urban spatial structure have various kinds of sizes, and among them there is the hierarchical relationship in terms of spatial relationships. In oder to it, I propose HVCM (Hierarchical Variable Clumping Method) based on VCM for exploring clusters of urban economic activities. For empirical case study, the business service industry was analyzed for Seoul. The business database for the analysis was constructed from the "The Korean Business Directory, 2007", and based on it, the cluster analysis was implemented by applying HVCM algorithm. As the results of the research analysis, the huge two clusters for the business service industry were explored; one in the central city and the other in the Gangnam region. The business industry in Seoul shaped the polynucleacted urban spatial structure, and located in the urban centers. Furthermore, the spatial hierarchy among various clusters was detected. The research will help the incoming research for urban polynucleated spatial structure and exploration of the centers, and in regard to this, more attentions and researches on spatial cluster methodology will be needed.