One of problems in Korean housing loan markets is that most of the maturities of housing loans are so short that often borrowers are exposed to risks following the frequent changes in the volatile domestic housing markets and financial environments on the whole. Since year 2011, accordingly, the Korean government has made some policy initiatives to encourage the conversion of some portions of existing short-term housing loans into long-term mortgages. As mortgage back securities (hereafter MBS) are the financing resources for long-term mortgages, the MBS market should be developed to succeed in that policy. The objectives of this paper are to study the current problems and constraints in the MBS market and then suggest the policy implications for advancing the MBS market. This study stressed that, for the development of MBS market without pausing any threat to the financial market stabilization, two things should be taken into consideration in implementing the policy. First, the credit qualities of MBS' underlying assets should be kept at certain level risk. Second, the government should control the aggregate liquidity to prevent the MBS from leading to the oversupply of housing loans. Considering the investors' general attitudes and capabilities, the potential demand for MBS is not expected to be sufficient to match the increasing supply of MBS. According to our estimation, the outstanding amount of MBS will be 68 Trillion Won on the condition that the 30% of banks' housing loans will be converted to the long-term mortgages at the end of year 2016, while the investors including insurance companies and public and private pension funds will have the capacity of holding only up to 55 Trillion Won. Therefore, the demand for MBS is likely to fall behind its increased supply. This paper, accordingly, reviewed several ways in which the demand for MBS can be raised under a number of possible scenarios. According to our scenario tests, the most doable way to increase the demand for MBS is to somehow improve the investors' risk attitude toward MBS so that the investors will be more willing to hold greater portions of MBS in their assets. As the insufficient demand for MBS may make it more difficult to restructure the housing loan markets, the government also needs to devise a scheme to further boost the MBS market. This study suggested two measures to expand the demand for MBS. First, the liquidity of MBS should be enhanced to attract more investors. This can be achieved mainly in two ways: one way is to adopt the ‘fungible issue scheme' for MBS, and the other is to simplify its tranches. Here, by the fungible issue, we mean that issuers supply the bonds with the same coupons and maturity dates within some period even if the issue dates are different. The scheme is to make investors regard those bonds as the same types of bonds. On the other hand, among tranches of MBS issued by KHFC, the seven-year maturity tranche is least liquid. We, therefore, suggest that the seven-year maturities are to be replaced by more of five-and ten-year tranches. Second, the government can set in place policy initiatives to increase transparency by wider scope of disclosure on the information of MBS. This will help increase the demand for MBS in the long run because improved transparency can certainly strengthen the investors' confidence in the credit quality of MBS. Currently, as the information of each underlying asset of MBS is scarcely disclosed to investors, they evaluate the credit risk of MBS based not on the assessment of the qualities of underlying assets but on the guarantee of KHFC. As the investors currently set investment limits on MBS in line with the size of guarantor's capital, it is necessary to forge an environment in which the investors can begin to rely more on underlying asset qualities, independently of the issuers. It is evident that the restructuring of housing loans from short-term lending to long-term mortgages has limited efficacy as a solution to the current problem of housing loans. While the policy may alleviate the vulnerability of housing loan markets to liquidity shock by diversifying the maturities of housing loans, it cannot alone solve the insolvency of housing loan borrowers, especially that of lowest income households. Therefore, the restructuring of housing loans should apply to only the borrowers who have the capability of solvency. This is because if the insolvent borrowers get the long-term mortgages, it will only increase credit risk in the financial market, further exacerbating its stability. In addition, financial policy alone are not sufficient to solve the aggravation of household credit risk and the insolvency of some household loans. More coordinated policies with other sectors such as employment and social welfare policies may significantly increase the chance of success. Though the financial aids may offer transient solution to some household borrowers' shortage of liquidity, in the longer term, it can only add more burden on them as more aid means more amount to pay back in the future. Also housing loan problems stem from layers of issues surrounding Korea's household loan markets. To start with, the household asset composition is heavily concentrated on real estates. Also, banks are reluctant to issue non-collateral loans, and the bankruptcy system has to be further advanced to meet the challenges of current financial market. Therefore, the restructuring scheme of housing loans can only make the limited contribution to solving the housing loan problems. However, the restructuring scheme is important because it will ease the current liquidity problem caused by the concentration on maturities of housing loans. As a result, the policy will be effective measures to prevent the housing loan problems from having a spillover effect on real economic sectors, causing economic crisis.