Sŏksŏngsansŏng () was a Baekje-era Korean fortress in what is now Buyeo County, South Chungcheong Province, South Korea. On January 21, 1963, its former site was made a Historic Site of South Korea.
The forterss was built in the first half of the 6th century to protect the Baekje capital Sabi. It connected to the other fortresses Hwangsansŏng, Nosŏngsansŏng, Sŏnghŭngsansŏng, and Kŭmsŏngsansŏng.
It is located on the summit of the mountain Pajinsan (). It has three sets of walls. The outermost wall has a perimeter of and an internal area of . The second wall has a circumference of and area of . The third wall has a circumference of and area of . There were 7 gates at the fortress.