MARPOL ANNEX Ⅵ, regulation14 deals with Sox Emission Control. The key contents of regulation14 are emission standard that apply to global area and ECAs that apply particularly high standards. In AppendixⅢ, it also includes procedures for designating ECAs. According to thes content in order to designate an ECA, a procedure to cooperate with neighbouring countries, secure validity through scientific evidence and the consent of IMO member states are necessary. However, some countries are desighnating ECAs under their own domestic laws. This is judged to be because the designation of the ECA can be applied easily and promptly through demestic laws. Meanwhile, the IMO convention and the UNCLOS member states’s demestic laws must ensure compatibility so that the UNCLOS and its contents do not clash with one another. Additionally, UNCLOS differentiates the jurisdiction of coastal countries according to the status of the maritime domain. in other words, the absolute jurisdiction of coastal states in inland water, limited jurisdiction that do not interfere with innocent passage in territorial waters, and jurisdiction meets international standards in the Exclusive Economic Zones are granted. However, the ECA under the domestic laws of some countries regulate foreign ships, going beyond the jurisdiction stipulated by UNCLOS. Therefore, in the short term, it is necessary to redesignate the ECA, and in the long term, an international ECA should be designated according to MARPOL’s procedures, and a joint emission control area should be designated through the cooperation with neighbouring countries.