This article is to study on the North Korea (NK)'s Terrorism and Provocations after the Korean War against the Republic of Korea and Its Countermeasures. In this article, I studied about the organizations of terrorism and provocations against the Republic of Korea (ROK) after the Korean War (1950-1953). And, I suggested the measures of counter-terrorism. A cases of the provocations by NK after the Korea War were studied periodically and each ruling governments. In the study, many types of terrorism suca as assassinations against VIPs, kidnapped of hostages, suicide bombing and demolition, aircraft terrorism, attacks against airline facilities and their users, vessels kidnapped and demolition on the sea, terror on the cyber, terror by weapons of mass destruction (WMD) were studied. NK mostly executed terrorism such as assassinate against VIP, aircraft terrorism, kidnapped civilians and fishing boats capturing, and terrorism against the major facilities. The characteristics of terrorism against the ROK are as the followings; ① direct support for terrorism by the NK, ② objectives of terrorism are limited to the ROK, ③ violent terrorism is supported for strengthening the international revolutional power, ④ purpose of reducing the internal dissatisfaction of the NK and making tensions, and raising anti-ROK feeling, ⑤ minor excuse statements about the terrorism executed by the NK, ⑥ making chances for division and disorder of the ROK and unification by the NK. In conclusion, the probable terrorism and provocations against the ROK by NK are exist. NK will execute terror and provocations against the USFK factualities too. And NK will use the nuclear weapons and missiles, I can suggest the countermeasures for terrorism against NK such as understand and application about strategies for counter-terrorism, enforcement of international cooperations for preventing tense against the ROK by NK, establishment of response measures for terrorism by NK.