The purpose of this study is to find success factors of knowledge management in Korean firms, confirm them empirically, and verify their relative importance in terms of company size and industry type. The major studies on the knowledge management were deliberately selected and interpretively analyzed to find the success factors of Korean firms. As a result of the analysis, five success factors(top management's will, evaluation reward, organizational culture, knowledge management system, organizational structure) have been found. The empirical researches to make certain whether the above five factors derived are actually true or not have been separately performed by using questionnaire method. Based on the data collected, it is found that all five factors are significant. The degree of relative importance among the success factors of knowledge management in Korean firms has been found as: (i)top management's will, (ii)organizational culture, (iii)evaluation-reward, (iv)knowledge management system, (v)organizational structure. In company size, large firm's degree of relative importance among the success factors are: (i)top management's will, (ii)organizational culture, (iii)evaluation-reward, (iv)knowledge management system, (v) organizational structure. And medium-small firm's degree of relative importance among the success factors of knowledge management in Korean firms has been found as: (i)top management's will, (ii)organizational culture, (iii) evaluation-reward, (iv)knowledge management system, (v)organizational structure. Finally, in type of industry, manufactural firm's degree of relative importance among the success factors of knowledge management in Korean firms has been found as: (i)top management's will, (ii)organizational culture, (iii)evaluation-reward, (iv)knowledge management system, (v)organizational structure. And non-manufactural firm's degree of relative importance among the success factors of knowledge management in Korean firms are: (i)top management's will, (ii)organizational culture, (iii)evaluation-reward, (iv)knowledge management system, (v)organizational structure.