Terms of trade shocks have been considered one of the main driving forces causing business cycle fluctuations in small open economies. Despite their importance in business cycles of small open economies, it is hard to find a serious study in existing literature investigating their implications on monetary policy under a small open economy. Considering it, this paper studies what form of monetary policy rule is the most adequate for a small open economy where terms of trade shocks are dominant factors in generating its business cycle fluctuations. For this purpose, various implementable monetary policy rules frequently analyzed in existing literature are compared in terms of social welfare levels which they can provide for the economy respectively. Main results of this paper can be summarized as follows. First, for a small open economy where terms of trade shocks are main driving forces of its business cycle fluctuations, the nontradable goods price inflation targeting can provide higher level of social welfare than other traditional monetary policy rules such as the CPI inflation targeting or the fixed exchange rate regime. Second, the social welfare improvement of the non-tradable goods price inflation targeting is more apparent when export goods price shocks are more important than import goods price shocks.