This study discusses firstly theoretical framework to specify housing subsidies under the concept of housing affordability, which implies households should be able to meet the housing consumption which society regards as a socially-desirable minimum within the reasonable burden on their incomes and without failing to enjoy the non-housing minimum consumption. Therefore it defines both the households that do not have the housing affordabilities and among them the households that housing subsidies should be paid by all means. This study argues that housing subsidies should be targeted to the households whose real incomes do not meet the level of consumption expenditures required for the socially-desirable minimum standards of both housing and non-housing consumption and that the amount of housing subsidy of each household becomes the gap between their minimum level of consumption expenditures and their real income. Secondly this study estimates how many households are not housing-affordable and require subsidies and tries to compute the amounts of housing subsidies for them using the survey data in 2002. This study contributes to present logical methodology for housing subsidy system, to estimate the number of adequate recipients and to compute the amount of housing subsidies. Also this study can be very useful to policy-making decisions for housing welfare of low-income households.