Hyōnosen-Ushiroyama-Nagisan Kokutei Kōen (氷ノ山後山那岐山国定公園) is a Quasi-National Park in Hyōgo Prefecture, Tottori Prefecture, and Okayama Prefecture, Japan.

[1][2] It was founded on 10 April 1969 and has an area of 488.03 square kilometres (188.43 sq mi).

[3][4][5] Hyōnosen-Ushiroyama-Nagisan Kokutei Kōen comprises three areas of the Chūgoku Mountains, a mountain range which forms the backbone of the Chūgoku region of western Japan and extends under the Pacific Ocean.

[4] The park covers 48,803 hectares (120,590 acres): 25,200 hectares (62,000 acres) in Hyōgo Prefecture, 15,024 hectares (37,130 acres) in Okayama Prefecture, and 8,579 hectares (21,200 acres) in Tottori Prefecture.

Important mountains of the park include: