The purpose of this study is to examine the relationship between core factor of Knowledge Management(KM) and organizational effectiveness. The objects of study are middle manager in hosing construction and civil engineering and construction industry, and the sample size is 228. The core factor of KM and indicator of organizational effectiveness are drawn by literature survey. The core factors are classified into human capital, organizational capital, structural capital, (to put it concretely), job capability, human relation, strategy, information technology, process, sharing culture, leadership, measurement. The indicator of organizational effectiveness are measured by job satisfaction, organization loyalty, competitiveness. The main results of this study can be summarized as the following. 1) The core factor of KM has a positive relationship to organizational effectiveness. Especially, the core factor of sharing culture and leadership are strongly relationship with organizational effectiveness. 2) There was a high positive correlation between job satisfaction and organization loyalty. 3) Human, structural, and structural capital had a different affect on organizational effectiveness. 4) The more job position and educational level high, the more they recognized that KM is necessary for their organization. 5) Among the success factor in KM, the factor of job capability was well perceived to respondent. According to this study, we can analyzed the relationship between success factor and organizational effectiveness, and drawn the most influence success factor on organizational effectiveness. Concurrently, the results of this study will be useful guidelines for shaping the KM operation framework in construction industry.