Iga Ueno Castle, Japanese castle in Iga, Japan.

Iga Ueno is a Japanese castle in the heart of Iga city, perched on a hill between two rivers. The wooden structure rises behind massive stone walls that climb steeply from the surrounding moat and protect the fort.

Oda Nobunaga conquered Iga in 1581 and installed Takigawa Yukitoshi, not Katsutoshi, as guardian; the castle itself was built from 1585 by Tsutsui Sadatsugu on the ruins of Heiraku-ji. Tōdō Takatora took over after 1600 and raised the honmaru walls to about 30 metres, among the tallest in Japan. His new five-story tenshu collapsed in a storm in 1612 and was never rebuilt after the Siege of Osaka in 1615.

The castle stands on the site of the Iga ikki headquarters, the self-governing league of ninja families that ruled the province until Oda Nobunaga's conquest in 1581. The Iga-ryū Ninja Museum next to the castle displays a model village and ninja history. The castle is also called Hakuhō-jō, or White Phoenix Castle, for its architecture and floor plan.

The castle is about a 30-minute walk from Iga-Ueno Station on the JR West Kansai Main Line, or a 5-minute walk from Uenoshi Station on the Iga Railway. The honmaru walls reach 29.7 metres, and the reconstructed keep is a 3-tier, 3-storey wooden tower on a stone base. The castle grounds are open as Ueno Park, and the keep interior can be visited.

The current main tower did not arise from official initiative but through the personal commitment of a local representative who funded the project in the 1930s. Inside this tower, a museum now displays collections on regional history that cover weapons, armor, and household items from several centuries.