The high-rise and high-density condominium reconstructions initiated by developer had lots of bad influences to urban environment in Korea. Recently, to restrict the high-rise and high-density condominium reconstructions, legal regulations are being strengthened. As a result, condominium reconstruction is facing the decreasing of feasibility and the difficulties of developer' s positive participation. Therefore, there will be needed the owners-initiated reconstruction activities. As a first phase of whole study, in this paper, we aimed to clarify the process of consensus building on the owners-initiated condominium reconstruction by case study. The main conclusions are as follows." l) The owners-initiated reconstruction was realized by the efforts to solution the oppositional views among the parties concerned. 2) The promote organization with high decision making ability showed strong readership to the other parties concerned. 3) The relationship of mutual trust between promote organization and the other owners was established. 4) The partnership between promote organization and professionals or developer was established.