In order for a professional baseball player to play in the league, the KBO (hereinafter referred to as the Korea Professional Baseball Organization) must sign a player contract with the club in accordance with a pre-written “unification contract.” The KBO has been revising baseball rules more than several times through board meetings, and its role in protecting players rights, resolving disputes, and enforcing proxy control has been strengthened. Many theories also view professional sports players contracts as “special employment relationships”, a mix of civil law, labor standard law, and contract regulation laws, while supporting the nature of employment contracts. Meanwhile, the speciality that professional baseball contracts must be signed within the KBO s self-governing rules requires a harmonization of the legal interests of the teams and players. This is because these studies are consistent with the combined objective of establishing a reasonable contract between the competitor and the club.