We develop an optimal-control general equilibrium model of the optimal taxmix among the labor income tax, the capital tax and the consumption tax,which incorporates the trade-off between the efficiency and the equity. Weexplicitly consider a flexible social welfare function that assigns differentweights on the efficiency measured by per-capita GDP and the equitymeasured by Gini coefficient. It turns out that the current tax mix of Koreaputs more weight on the efficiency (0.6~0.7) over the equity (0.3~0.4).Regarding the possible tax reform in the future, we should increase the ratioof the consumption tax to GDP by 0.23~0.66%p if we put higher weight onthe efficiency side. If we put higher weight on the equity side, we shouldincrease the ratio of the labor income tax to GDP by 0.09~0.50%p. Finally themodel suggests that the optimal portion of the capital tax does not respondmuch to the changes in the social preferences represented by the changes inweights on the efficiency and the equity.