Sōka (草加市, Sōka-shi) is a city in Saitama Prefecture, Japan. As of 1 February 2021[update], the city had an estimated population of 249,645 in 118,129 households and a population density of 9100 persons per km². The total area of the city is 27.46 square kilometres (10.60 sq mi).
Sōka is situated in the southeast corner of Saitama Prefecture approximately 30 kilometers away from downtown Tokyo. It is surrounded to the east by the cities of Yashio, Misato and Yoshikawa, and to the west by Kawaguchi. To the north is Koshigaya and to the south Adachi Ward of Metropolitan Tokyo.The city is in the center of the Kanto Plain and is mostly lowland with an elevation of only three meters above sea level. The Ayase River flows through the city, which was subject to frequent flooding despite various flood control measures taken since the Edo Period.
Sōka was once a peaceful agricultural area surrounded by water and greenery, but as a result of urbanization, the once abundant greenery and clean water was adversely affected. Now, Sōka is promoting a "town of greenery and water based on history and the natural features of the area". Creation of areas of greenery reflecting the changes of the four seasons, and the restoration of waterways and environs is being advanced.