Mt. Oseongsan made up of five peaks is a noted mountain whose chain and range are close to Geumgang River, and it is the highest in Gunsan. Although the mountain is 227 meters above the sea level, you can have a bird's-eye view of the town of Gunsan and the middle and the lower of Geumgang River, Oksan Plain of Okgu, and Seocheon in Chungcheongnam-do on the top, where the stream of Geumgang River looks like a strip of calico. It is a natural observatory where we can see Gunsan Port, various ships coming and going, Mt. Gongjusan in Chungcheongnam-do, and even Mt. Mireuksan in Iksan.
An old tale says that five old men in Baekje Dynasty era playing paduk in Mt. Oseongsan refused to show the way saying "we are Baekje people and will not show the way to those who invade Baekje" when a general of Dang Dynasty of China invading Baekje asked them for showing the way to Buyeo. Undoubtedly, the five old men are beheaded by the soldiers from Dang Dynasty, and they have been called Oseonghyeon, five sages. "Oseong Cutural Festival" is held in honor of the spirit of Baekje people and the harmony of the citizens of Gunsan. In every early October, the memorial service in Confucian ritual is held in front of Tomb of the Five Sages on the top of Mt. Oseongsan and have variegated functions. They select a "Oseong Old Man" of old men over 85 years old who are renowned for their virtue and make a contribution to the community. There are many assorted culture and art events including a service for repose of the deceased, Pansori (traditional long epic song), Samulnori (tradition percussion quartet), and the instrumental music of peasants. The service for repose of the deceased is performed by a shaman in order to solace the malignant spirits killed defending the country, which is the highlight of the festival.
There is a large rock called Fairy Rock on the mid-slope of the mountain. An old tale says that the fairies used to enjoy themselves looking at the world there, and the footprints left on the rock are said to be the fairies'.
Mt. Oseongsan is 30 minutes' away from the downtown and 5km from Geumgang Estuary Bank, and it has the place for practicing paragliding and an observatory. The earthen ware used by the people of the Neolithic Age, shell mound, and dolmens are being recovered around the mountain, and there are Jinseongchang, the place where General Choi Mu Seon gained a signal victory, the site of an ancient castle, and the place for signal-fire on Dojinsan.

Tourist attractions : Tomb of the Five Sages, Paragliding Place.