This paper argues that peaceful coexistence of South Korea and North Korea should be pursued instead of peaceful unification because peace and unification contradict each other in the Korean Peninsula. Comparing the positions of South Korea and North Korea on unification to substantiate this claim, this paper will reveal that South Korea and North Korea have demanded exchanges and cooperation from each other according to their own circumstances. South Korea and North Korea advocated peaceful unification while having a hidden intention to unify by absorption under their own system, such that unification did not progress, but rather, conflicts and confrontations were amplified. South Korea, which had an absolute advantage over the economy, argued for North Korea’s reformation and opening up expecting North Korea's collapse and unification by absorption or promoting peaceful coexistence. Knowing this, North Korea armed itself with nuclear weapons to gain a military advantage. Since South Korea and North Korea cannot renounce their national identity as respectively stipulated in the Constitution and the Labor Party rules, especially since North Korean leader Kim Jong-un cannot give up his power, neither reformation and opening up nor unification is possible. This paper argues that what we should pursue in such situation is not a peaceful unification, but rather a peaceful coexistence. That is, this paper argues that the theory of peaceful unification should be abandoned and that the theory of peaceful coexistence should be promoted.