The purpose of this paper is to estimate the revenue function of the personal income tax of Korea. Unlike the traditional approach employing the data adjustment, this paper explicitly includes the explanatory variables of the tax rate or schedule in the revenue function and further estimates the functions by income sources such as labor, interest, global, and dividend incomes. One of the main findings is the GNP elasticity of the combined personal income tax is around 1.2 when evaluated on the basis of the estimates of the GNP elasticities of tax revenue from respective income sources, which is somewhat smaller than those in the previous studies. Another interesting result is that the GNP and interest rate elasticities of the interest income, are found around one and .15 respectively, as expected. Also, the estimate of the tax-free income coefficient is significantly negative in the labor in­come tax revenue function.