Osaka Castle Park (大阪城公園, Osaka-Jō-Kōen) is a public urban park and historical site situated at Osaka-Jō in Chūō-ku, Osaka, Japan. It lies on the south of the Ōkawa (Kyū-Yodo River) and occupies a large area in the center of the city of Osaka. This park is the second largest park in the city.
The park was constructed on a site with a long history. In the fifteenth century, a militant temple, Ishiyama Hongan-ji, was built here. In 1583, Toyotomi Hideyoshi destroyed Ishiyama Hongan-ji and built Osaka Castle here. From 1870 to 1945 the Osaka Imperial Arsenal used a large area, and it was destroyed at end of World War II. In 1931, Osaka Castle Park was opened to the public, but most of the area was used by the Imperial Japanese Army. After World War II, most of the military complex was removed and replaced by the public urban park.
In the park, there is Osaka Castle Hall, a large athletic field, baseball field, football field, open-air music theatre, open-air concert hall, and Osaka Castle Keep Tower. From the top of keep tower, the vista includes Osaka Bay to Mount Ikoma, which surround the Osaka Plain. Many busking groups perform in the park. In spring, cherry blossom and plum blossom viewing is popular at this park.