The fighter, presumed to be a KA-1 light attack aircraft, crashed in Hoengseong county, some 140 km east of Seoul, at about 11:40 a.m. local time (0240 GMT), Yonhap news agency reported Monday.
The two pilots aboard escaped safely and were transferred to a nearby hospital. The combat plane fell in a field, and no civilian casualty has been reported yet.
The military authorities were reportedly investigating the exact cause of the crash.