Tomioka Castle, Japanese castle in Amakusa District, Japan.

Tomioka Castle is a hilltop castle (hirayama-style, terraced) on the southeastern part of the Tomioka Peninsula, a tied island of Amakusa Shimoshima joined to the mainland by a sandbar. Its honmaru holds a restored yagura serving as the Tomioka Visitor Center, with a restored Koma gate and stone walls; white plastered ranges with grey stone bases and low grey roofs stand along the wooded crest.

Terazawa Hirotaka built the castle between 1602 and 1605 as a reward for his service in the Battle of Sekigahara. During the Shimabara Rebellion in 1637, the site came under attack from Christian rebels but was successfully defended.

The hilltop keep now houses the Tomioka Visitor Center, which presents Amakusa's history, culture and nature. On the ninomaru grounds stands the Reihoku Town History Museum, beside two monuments: one with bronze statues of Suzuki Shigetane and his brother Shōzō, the other of Katsukai Shū and Rai San'yō. An Inari shrine sits below the ninomaru toward Tomoe Bay.

The visitor center in the restored keep of the honmaru displays Amakusa's history, culture and nature. From the ninomaru car park, a path leads down toward Tomoe Bay past an Inari shrine, and the Adam Arakawa martyrdom park with three monuments lies just below the car park. By bus, take the Amakusa-go from Kumamoto to Hondo Bus Center, change to the Tomioka Port line and get off at Itchome, then walk about 14 minutes (1.1 km).

The castle's defences relied on nature: the tidal inlet of Tomoe Bay and the sandbar formed natural ramparts, and the only land approach was across the sandbar. The moat role was played by the Fukuike pond south of the castle. The keep area now holds the Tomioka Visitor Center, rebuilt by 2005 from the Edo-period Hizen Amakusa Tomioka Castle plan.