A Study on the Revised Civil Code Concerning Japan’s Owner-Unknown Land Issue : Focusing Especially on Co-Ownership Relations

This paper analyzes the issue of “owner-unknown land” in Japan, which has become a serious social problem due to rapid aging, population decline, and unregistered inheritance, and examines the amendments made to the Civil Code and related special laws in 2021. Focusing particularly on the legal concept of “co-ownership” under the Civil Code, it systematically reviews how recent legislative changes have brought institutional shifts in the use, management, alteration, and division of co-owned properties. Owner-unknown land refers to land where registered owners exist on record but the actual owners cannot be identified or cannot exercise their rights due to unknown addresses or unclear survival status. Such land accounts for approximately 20 to 24 percent of Japan’s total territory, causing significant obstacles to land utilization and regional development. The problem has been exacerbated by population decline, extreme aging, repeated inheritance, and changes in family structures. Against this social backdrop, the issue was seriously highlighted during the reconstruction projects following the 2011 Great East Japan Earthquake, and subsequent research and reviews by both private sectors and government agencies led to the enactment of the Special Measures Law in 2018, amendments to the Civil Code and the Real Estate Registration Act in 2021, and the enactment of the Law on National Treasury Succession of Inherited Land in 2023, marking a phased legislative response. The amended Civil Code particularly focuses on practical solutions for co-ownership issues. It relaxes procedures to enable the early resolution of co-ownership created by inheritance and introduces a registration obligation for all heirs to suppress the increase of neglected land. Furthermore, it allows courts to exclude absentee or indifferent co-owners from voting rights to revitalize decision-making processes, and rationalizes co-owned property management by permitting majority votes for minor modifications or management actions instead of requiring unanimous consent. In addition, a professional co-ownership manager system was established to address cases with numerous or geographically dispersed co-owners, enabling the manager to exercise sole management authority and certain judicial functions, thereby enhancing effective management. Lastly, when agreement among co-owners is impossible, the law permits judicial partition proceedings to commence solely on the basis of “inability to reach agreement,” facilitating efficient and prompt resolution of co-ownership disputes. Such amendments in Japan’s Civil Code provide important implications for South Korea’s Civil Code and Condominium Act. The exclusion of voting rights for absentee co-owners, enhancement of practical co-ownership management, formalization of the manager system, and expedited partition procedures offer useful institutional reform directions to address similar social issues caused by aging populations and dispersed inheritance. Moreover, these changes can positively contribute to resolving practical challenges such as aging building maintenance and urban regeneration. In conclusion, this paper reveals that Japan’s Civil Code amendments addressing the owner-unknown land problem represent a notable case of modernizing property management laws to respond effectively to complex social risks. It also emphasizes the necessity for South Korea to establish a sustainable property law system capable of efficiently handling the deficiencies in the registration system and the complexities of property rights. Thus, it calls for substantive discussions toward building an advanced land and property management framework that harmonizes efficiency, public interest, and rights protection.