This paper estimates the sales effects from implementation of emissions trading scheme on the Korean manufacturing sector. Under no free allocation scenario, sales reduction ranges between 0.75% and 2.64%, which amounts to KRW 8.4~29.6 trillion. Cement and iron & steel industries may suffer more than 5% decline in sales even under the most modest scenario. By taking account of the nature of emission and sales effects by sector, complementary measures are suggested to minimize the weakening of industrial competitiveness and carbon leakage. The most common measure is to allow a certain ratio of free allocation to the sectors significantly exposed to carbon leakage. Comparison of legislations and bills in the EU, Australia, and the U.S. is made to consider detailed factors regarding the selection of industry at risk of carbon leakage, which leads to coming up with the way best suited to Korea.