Wakayama Castle is a Japanese castle located in the city Wakayama, Wakayama Prefecture, Japan. For most of the Edo Period, it was the administrative center of Kishū Domain, which was controlled by a cadet branch of the Tokugawa clan. Due to its size and status, Wakayama Castle was ranked as one of the most important castles under the Tokugawa shogunate. The castle was designated a National Historic Site in 1931, and its Nishi-no-Maru Garden was designated a National Place of Scenic Beauty in 1987.

The Kishū Domain, also referred to as Kii Domain or Wakayama Domain, was a feudal domain in Kii Province, Japan. This domain encompassed regions in present-day Wakayama and southern Mie prefectures and had a substantial income of 555,000 koku. The administrative center of the domain was located at Wakayama Castle, which is situated in present-day Wakayama, Wakayama Prefecture.