Wakayama Castle (若山城, Wakayama-jō) is the remains of a castle structure in Shūnan, Yamaguchi Prefecture, Japan.

Its ruins have been protected as a Prefectural Historic Sites.

[2][3] Wakayama castle was built by the Sue clan, one of the most important retainers of the Ōuchi clan and became a home castle of the Sue clan in the Sengoku period.

[4][5] Sue Harukata improved and strengthened the castle before the Tainei-ji incident.

[4] The castle was attacked by the Mōri clan soon after the Battle of Miyajima, Harukata's son Nagafusa was defeated and he committed seppuku.