In order to establish order in fishing industry by cracking down on illegal fishing vessels effectively, it is an essential requirement to identify marking such as the name of fishing vessel and a port of register more easily. Accordingly, it is quite natural that markings on fishing vessels should be marked clearly in an appropriate size on an appropriate site in order for them to be distinguished on the air such as from planes as well as on the sea. Actually, when examining marks such as the name of a vessel which are operating in the country, marks of most fishing vessels are too small as they cannot be distinguished with the naked eye even very closely. There is no coastal fishing vessel which marks the name of fishing vessel on the upper part in order to distinguish it from planes. Fishing vessel law generally which regulates the basic laws about shipbuilding regulates marks on fishing vessel, and fisheries law only regulates sign boards of fishing vessels. Problems and improvement of the marking system on fishing vessels suggested by this paper are as follows. First, in order to contribute to establish order in fishing industry, it would be desirable to tighten standards in fisheries law besides the fishing vessel law. Second, it is difficult to distinguish marks such as the name of a vessel as relevant laws allow fishers to make such marks too small. It is necessary to set the standard for marks larger than those regulated by the international treaty. Third, the relevant laws do not regulate a letter form of marks. Therefore, it becomes a factor to make small marks hard to be distinguished more. It is necessary to decide a clear letter form. Fourth, there is insufficient detailed international standards about the marking system. It is necessary to regulate a detailed standard.