“Salubriousness of the City” and Public Baths in the Principate Rome Ryosuke TSUTSUMI The purpose of this paper is to examine a relationship between the governance and medical knowledge of Ancient Rome, focusing on the medical function of public baths and Frontinus’s concept of “salubriousness of the city (salubritas urbis)”. Some scholars associate the construction of public baths with “public health” policy based on the existence of bathing therapy in the ancient medicine. Others argue that there were not any health plans in Ancient Rome and Roman public baths did not have any connection with medical concern. In order to settle this controversy, I analyze the Roman medical theory and the ruler’s attitude to “salubriousness of the city”. Secondly, the concept of “salubriousness of the city” will be scrutinized in terms of medical interests of Roman rulers. ”Salubriousness of the city”, which Frontinus referred to as one of the duties of curator aquarum, is symbolized by the pure water and clean air. This concept is also attested in the letter of Pliny and Digesta. Finally, by examining the medical description of public buildings in Vitruvius’s “On Architecture”, I will redefine the concept of “salubriousness of the city”. This concept was restricted to urban environment and did not include anything relating to medical treatment. Based on these analyses, the author concludes that “Salubriousness of the city” was political issue for Roman rulers, thus restricted to urban environment. The medical treatment in public bath was out of their concern.