In this paper, I would like to examine the relationship between the copyright system and the freedom of expression of the Constitution among the legal systems in Korea. Focusing on copyright, I will discuss freedom of expression. Therefore, the discussion on freedom of expression under the Constitution theories is omitted. Both the copyright system, which has a form of property rights, and the freedom of expression stipulated in the Constitution are aimed at protecting expression, enhancing expression, and allowing it to be expressed more freely. However, in the copyright system, even obscene works, works with illegal content, or fake news works, which are antisocial expressions, are included in the protection area of the copyright law. Regarding parody, there is an institutional mechanism of copyright law that can guarantee freedom of expression through the formation of works, but Korean courts are quite passive in recognizing parody. The author's right to maintain the right of integrity can also be an important means of limiting the freedom of expression of others. However, there was a case of denying the infringement of the author's right to maintain the integrity by exercising the state's public power in Korea. In the case of the freedom of editing of a broadcasting corporation and the infringement of the author's moral rights, copyright infringement was affirmed based on the contract law rather than the freedom of editing. In Korea's copyright law, there are scattered systems that help free political opinions of not only media organizations but also ordinary citizens by restricting author's economic rights exercise. In addition, the Korean copyright law has a judicial systems that indirectly helps freedom of expression. Freedom of expression of the Constitution and copyright system of copyright law inevitably have a connection with expression, and there is something in common in history from the perspective of protecting expression. From now on, I think in-depth research is needed on both legal systems.