This study examines the development of inclusive parks in Japan by comparing international research findings with domestic guidelines and 59 park cases. The analysis identifies three major challenges: inconsistent definitions of inclusiveness, limited application of Universal Design for Play (UDP) principles, and insufficient participation of children with disabilities in the design process. While Japanese parks have improved physical accessibility through barrier-free routes and universal restrooms, sensory, cognitive, and social aspects of inclusion remain underdeveloped. The study concludes that Japan needs more comprehensive, play-centered approaches, including standardized definitions, participatory design, and greater public awareness to create truly inclusive environments.