We develop a dynamic stochastic general equilibrium model of a small open economy in which both price rigidity and financial friction exist. We compare two cases featuring different interest rate rules. Both cases use the standard Taylor‐type interest rate rules, but the second case also considers external debt levels. We find that when friction in foreign borrowing is large, adding an external debt level to Taylor rules improves welfare. The welfare curve, however, exhibits a hump shape because excessive reactions to changes in external debt reduce welfare.