In order for a baseball player to act as a player in the Korean Professional Baseball League, the player and the club must conclude a player contract under the unification contract , a standard player contract determined by the Korea Baseball Organization (KBO). However, since the 1982 Professional Baseball League started, the KBO has only recognized face-to-face contracts between athletes and team officials and has not allowed players to sign contracts through their agents. In accordance with the continuing demands of the Korea Professional Baseball Players Association (KPBA), the KBO has revised KBO Rules to allow players to conclude contracts through their agents from February 2018. According to the “KBO League Player Agent Rules”, a player agent must be certified through qualifications and examination as prescribed by the KPBA, and only an authorized player agent can conclude a contract with the club on behalf of the player. Player agents can negotiate contracts and salaries, apply for a salary adjustment and represent the adjustment for players. However, if a player contract is concluded under a unification contract, the freedom to decide the contents of the contract is virtually excluded because the matters concerning the rights and obligations between the player and the club are uniformly determined excepting the remuneration and contract period. Also, since the unification contract is unilaterally decided by KBO, the contract under unification is structurally disadvantageous to the player, and the rights of the player are easily infringed upon by unfair contract provisions. It is expected that the player contracts will be reasonably concluded and the protection of player rights will be improved as the player agent system is implemented in the Professional Baseball League. Because the player may conclude an annual salary negotiation or a player contract through an agent, the player will be able to concentrate on improving the performances, such as training. Also, as the valuation of the players becomes more objective, the players supply and demand market will become transparent and exchanges of the players will be more active. In professional baseball, however, the agents can consult with the club only with respect to the maintenance and contract period, and the other contracts are set according to the provisions included in the unified contract, so the expected effect is limited.