The original castle is presumed to have been built by the Imagawa clan, but it was completely destroyed by the attacks of the Takeda clan and Tokugawa Ieyasu. In 1585, the castle was restored by Tokugawa Ieyasu, who retired to this castle after he passed over his official position as Shogun to his son, Hidetada, in 1605. The castle town of Sunpu had flourished as the place where “Ogosho (the Cloistered Shogun)” resided. After Ieyasu’s death, the castle was put under control of the Sunpu domain or Sunpu Jodai (the top ranking retainer of the domain) till it was dismantled by the Meiji Restoration in 1869. Now many municipal government office buildings and schools stand on the site of Sunpu Castle ruins with Sunpu Park in its center. The donjon does not remain but Tasumi-guruwa (the southwestern outer compound) of Ninomaru (the second castle), Higashi-gomon Gatehouse and Zokutamonyagura (a corner watch tower) remain to the present time. Also the moat of Honmaru was restored to its original form.