North Korea is one of the most secretive countries in the world but the closed nature of North Korea has attracted people's curiosity for quite some time. Compared to other countries, there is very little news and information one can readily find about the country. Despite these challenges, some scholars have conducted research not only on North Korean politics and security issues, but also on North Korean culture and society by analyzing media products such as posters and music. In North Korea, music is not only an entertainment product, but also a tool utilized by the state party apparatus to disseminate propaganda. Although the content of these songs does not always reflect real historical development, one can get a good idea about what the government wanted to promote in each historical period. The purpose of this study is to investigate historical trends in North Korean propaganda through the lens of the lyrics of officially-released songs. To this end, a quantitative content analysis of more than 600 North Korean songs (about 10 per year) that appeared in officially-released song collection books from 1948 to 2014 was conducted. The results are as follows. First of all, the average number of words of songs hovered around 202 (Korean) words with not much variation across time, suggesting that government aimed to create catchy propaganda songs that are easy to remember and are not too complex. Secondly, the number of songs per year surged in the mid-1990s, which demonstrates the importance of music during Kim Jong-il's reign. Songs at this time were mostly used to inspire confidence and empower the people in the wake of a great famine. The decrease in the number of songs from 2006 to 2007 may be due to the government's focus on other areas such as nuclear weapons testing. Thirdly, the creators of the songs were primarily men, likely because they were better educated than women. However, the performers of the song were mainly women. Fourthly, as to the themes of the songs, during the Korean War, songs unsurprisingly served the war efforts. Songs of this period mostly emphasized patriotism, praised the heroism of the army, and showed confidence in victory. When the United States and Japan were mentioned in songs, they were usually described in derogatory terms, which is not too surprising given that the North sees these nations as their archenemies. South Koreans, on the other hand, were frequently described as "comrades", "brothers", etc. In addition to the well-known political-themed songs or songs praising leaders for institutional propaganda, there were also "Life Songs" that related to people's everyday lives, and there were even love songs. The prominence of "Life Songs" in the early 1990s showed that North Korean songs were changing. In the early 1960s, the juche idea emerged in songs along with other revolutionary movements Kim Il-sung himself launched (e.g. Chongsan-ri spirit or the Chollima Movement). The most important propaganda content in North Korea can be said to be loyalty to and praise of the leaders, along the lines of the personality cults the three leaders established during their respective reigns. Expectedly, many songs were dedicated to the leaders. Most strikingly, songs with the theme of "Kim Il-sung" were found to be distributed evenly from the beginning to end of the analysis, reflecting his status as the "eternal president" and founder of North Korea. When Kim Jong-il was recognized as the heir in the 1980s, songs praising him began to appear. After his sudden and unexpected death in 2011, songs praising his son and successor, Kim Jong-Un, started to massively surface. Overall, the juche idea, as the guiding ideology of North Korea, has been found consistently and constantly in songs since the 1950. Additionally, the term songun or military-first policy appeared in songs since the late 1990s, reflecting the leadership's decision to put more emphasis on national defense towards the end of the Cold War than on the socio-economic welfare of the people.