Divestiture is divided into the form of spin-off that transfers the assets and liabilities of a particular division of the divesting firm and transfers the stock of the buying firm in return for it and the form of drop-down that transfers the stock of the buying firm to the divesting firm. The provisions on the divesture system were enacted in the Commercial Law for the first time in Dec 28, 1998. The divesture system can be said to be the system that came into the world in the process of overcoming the foreign exchange crisis since the end of 1997. Because six years have passed since the divesture system was enforced, this study, unlike previous studies abroad, needs to present the need to test whether divestiture gets rid of the inefficiency of the internal capital market in Korea, through the response of the efficiency and disclosure effect of the internal capital market. Therefore, the purpose of this study was to investigate whether divestiture was aimed at getting rid of the inefficiency of the internal capital market of the divesting firm in conjunction with the disclosure effect of divestiture. As the internal capital market is more inefficient, the inefficiency can be removed by specializing in and concentrating on a particular division by means of divestiture. In case the investment opportunity of a particular firm is low compared to the average of the same industry(Tobin’s Q is low) but the amount invested in capital expenditures such as investment in tangible assets, it can be said that the capital raised by the firm was inefficiently invested. Accordingly, the disclosure effect of divestiture will respond positively as the internal capital market is inefficient before the divestiture. To attain the purpose of the study, this study sampled only 78 buying firms on which data were available from their divestiture closing report and the audit report of except the buying firms on which data were not available from their financial data of firms disclosing their divestiture over the period between 1999 and 2004. They were divided into 22 industries to compare the efficiency of the internal capital market of the divesting firm and that of the same industry, and 8,441firms-year was used to compute the efficiency of the internal capital market of the same industry. In the test model, cumulative abnormal return(CAR) was used as the dependent variable and the controlling variable for efficiency and size of the internal capital market and the controlling variable for the type of divestiture were used as the independent variable. As a result of testing, the following findings were obtained: First, the disclosure effect of divestiture showed that the abnormal return(AR) had the significant positive response at the -10 day and -2 day of the disclosure day. Cumulative abnormal return(CAR) continued to increase from the -10 day of the disclosure day to the disclosure day and tended to reduce since the disclosure day of the divestiture. Like previous studies abroad, the disclosure effect of divestiture generated the positive(+) abnormal return. Second, the disclosure effect of divestiture had the significant positive response at the level of 10% as the internal capital market was inefficient. That is, the efficiency coefficient of the internal capital market was -0.15965(t-value=-1.94). When 2-year data on the amount of capital expenditures before the disclosure of divestiture were to compute the efficiency of the internal capital market, the efficiency coefficient of the internal capital market was -0.04650(t-value: -0.28) which was negative but not significant. It is interpreted that the capital market responded more sensitively to the inefficiency of the internal capital market of the years shortly before divestiture than that of the 2-year period shortly before divestiture. There was no difference in the findings of the study though reflecting such controlling variables as the variable of the type of divestiture representing spin-off and drop-down and the size of the total asset divested from the total of the divesting firm. Accordingly, the study hypothesis was supported that the disclosure effect of divestiture would appear positively as the inefficiency of the internal capital market is greater. Therefore, it is thought that the firm having several business divisions can promote corporate restructuring and improve the efficiency of investment by restructuring the internal capital through divestiture. Seeing that empirical studies have poorly been conducted on divestiture at the point in time when six years have passed since the divestiture system was enforced, it is expected that this study will be the starting point for an empirical study on divestiture.