Purpose: Designing a physiological sanitary space while taking user behaviors into account is influenced not only by functional and equipment elements but also by cultures, habits, and national characteristics. Public housing is a prime example of it, as its design reflects both the culture and spirit of the country while fulfilling the material aspects of living. Therefore, by adopting the standardized design of the Japan Housing Corporation, the current study aims to analyze the physiological sanitary space and the temporal transition process of physiological sanitary spaces, which derive from the blend of traditional and Western living cultures along with advancing technology, and to examine their unique spatial characteristics. Method: The research method first involves a theoretical review of physiological sanitary spaces in Western and Japanese residences through literature, defining functional unit spaces according to daily activities, and summarizing the standard design and equipment-related plans of public housing chronologically. Next, the unit plans are analyzed based on standard design drawings to identify changes and characteristics of unit spaces over time and to derive the spatial composition and characteristics of sanitary spaces. Result: The Japanese unique sanitary space in public housing, known as 'Mizumawari,' which is supported by functional segregation based on activities and Westernized facilities, emerged from the Western concept of integrating multiple functions within limited physical areas to promote effective use. This basic plan has been maintained even as standard designs were abolished and progressed to general-purpose and specialized designs.