Modern Joseon Architecture is North Korea's unique building style that interprets Korean traditional architecture in a modern way, and its most distinctive design feature is the Paljak roof that decorates the upper part of the buildings. This paper argues that continuous attempts at characterizing the nature of traditional Korean architecture in the late 1950s and early 1960s developed the theoretical rationale for the exclusive use of the Paljak roof in Modern Joseon Architecture. It also argues that the construction of the Pyongyang Grand Theater and the Okryu Restaurant during this period became a decisive moment for the formalization of the Paljak roof. The double roof rafters and gables and the "cheerful yet solemn" roofline were considered as main characteristic features of the Korean roof and the Paljak roof perfectly fits this description. Particularly, in North Korean society where Kim Il Sung became idolized as an impersonalized deity, an anecdote in which Kim Il Sung fixed a prominent gabled roof in the Pyongyang Grand Theater into a Paljak roof has allowed for the roof to gain an exclusive status. Hence, almost all Modern Joseon Architecture since the 1960s accepted the Paljak roof’s monopoly position, rather than experimenting with other traditional roof types.