On July 8, 2022, the world was shocked when the former Prime Minister of Japan was shot and killed by a homemade gun. In recent years, accidents by simulated guns or homemade explosives have occurred one after another. In Korea, where the management of firearms and explosives is relatively strict, firearms are being converted and traded illegally, and gun control, such as the death of a police officer due to a simulated gun, is at a dangerous level. Therefore, we will analyze the current state of management of simulated guns and homemade explosives, as well as improving the problems of the current Act on the Safety Management of Guns, Swords, and Explosives (hereafter, the Gunpowder Act). In addition, this study was conducted for the purpose of examining the possibility of being used in crimes and terrorism by unspecified majority and suggesting countermeasures. For this purpose, literature research and a case study were conducted as a research method. For the literature study, we reviewed academic journals, contributions, and government agency research reports for related prior research papers to derive areas that need improvement in reality by examining the regulations of the Guns and Explosives Act related corporations. In addition, we searched for publications published by newspapers or the National Police Agency, police white papers, and related data published by the National Assembly member's office, confirmed objective facts, and studied representative domestic and foreign cases that have occurred so far. As a result of this study, problems such as gun licensing, gun management, illegal possession/modification and smuggling of guns, education issues when obtaining permission to possess firearms, and non-compliance with safety rules were derived under the Guns and Explosives Act. There were also loopholes in gun management using 3D printers. As revealed in the case, these vulnerabilities can be used not only for simple crimes in the future, but also for terrorism. Therefore, as a further measure, it is necessary to establish and practically operate legal and institutional measures, measures of related institutions, administrative agencies, and legislative branches, and cooperative governance between the public, private, military, police and academia. In Korea, guns and explosives that can actually be used as weapons, such as guns, swords, explosives, gas sprayers, electroshock weapons, and crossbows, are thoroughly managed under the Guns and Explosives Act based on a relatively stable state of security, so accidents are rare. However, there are legal and institutional problems that control this, and there are constant exposure to illegal activities, such as crimes caused by simulated guns and homemade explosives, which are not stipulated in the relevant laws. There is a possibility that these vulnerabilities may be used by domestic autonomous terrorist groups or groups linked to international terrorist organizations for terrorism targeting an unspecified majority. Therefore, in order to maintain the current state of security, it is necessary to prepare practical measures such as supplementation of legal and institutional devices such as the Guns and Firearms Act.