From the social conflicts between groups of Eastern and Western Germans after unification, it can be inferred that prejudice could be a potential problem for Korean reunification. The three studies reported in this paper investigated methods to provide ways to reduce explicit (conscious) and implicit (nonconscious) aspects of prejudice of South Koreans against North Korea (study 1 and 2) and against North Koreans (study 3). In Studies 1 and 2, we found that explicit prejudice was affected by temporary exposures to relationships concerning South and North Koreas, but implicit prejudice was not. In Study 3, however, we found that implicit prejudice was reduced by repeated exposure to positive associations with “North Korean”. Scientific and political implications of the malleability of the two aspects of prejudice for psychological unification are discussed.