Jōnan-ku is one of the seven wards of Fukuoka City, Japan. As of November 1, 2004, it had a population of 128,057 people, making up 9.2% of Fukuoka City, with an area of 16.02 km2. At the time of Fukuoka City's official designation as a City in 1972, the area now known as Jōnan-ku was part of the larger ward of Nishi-ku. On May 1, 1982, Nishi-ku was subdivided into the three smaller wards of Nishi-ku, Sawara-ku and Jōnan-ku.