| Location | Osaka Pref. |
|---|---|
| Shape | Keyhole-shaped mound |
| Mound length | 160 m |
| Period | Early 5th c. |
| Designation | National Historic Site |
An approximately 160m-long keyhole mound in Otake, Yao, and the largest in central Kawachi. Built in the first half of the 5th century, it has three tiers, stone-faced slopes, and rows of cylindrical haniwa on its terraces. A National Historic Site, it is open as an archaeological park following conservation work. Its name is said to derive from Shinkoji, a Hata clan temple that reportedly stood in the area.
Three burial facilities were identified in the rear circle, yielding armor, mirrors, and other objects. A projection produced an unusual haniwa representing a water-ritual setting, with a house and enclosure modelled together.
Freely open to the public as "Shionjiyama Kofun Park"; one of the few kofun in Osaka where visitors can climb to the summit, popular with families. The adjacent "Shionjiyama Kofun Learning Center" displays excavated haniwa and excavation records, offering an introduction to Kofun-period culture. Replica haniwa line the park, evoking the ritual setting of the time. About a 25-minute walk north of Kintetsu Hattorigawa Station, or by bus from Kintetsu Kawachi-Yamamoto Station. Parking available. The park is free to visit; the learning center's exhibition room charges admission (¥240 general).