The housing finance market of Korea is deemed to be vulnerable to external risks. Combined with high burden of household debts, it may jeopardize the whole financial system. This study, based on this perception, identifies major determinants of loan delinquency from individual lending data. Compared with the existing empirical research on the same issue, the paper distinguishes itself by including loan characteristics as well as DTI and LTV for explanatory variables. The loan characteristics are proxied by maturity, payment, and the level and the variability of interest. Empirical results confirm that high levels of LTV and DTI both raise the probability of delinquency whereas a long-term amortizing mortgage tends to lower the probability. These results provides support that the government programs taken since 2000s, such as setting DTI ceilings and propagating long-term amortizing mortgage programs, should be pursued in the same direction.