The discovery was made at about 6 p.m. near Platform Bridge Road in an unincorporated part of the county, Marin County sheriff's Lt. Doug Pittman said.
The land is operated by the National Park Service, according to Point Reyes National Seashore spokesman John Dell'Osso.
Platform Bridge Road has been closed between Sir Francis Drake Road and Point Reyes-Petaluma Road, as investigators continue to search for evidence. Dell'Osso estimated the road would remain closed for the next several hours.
Sheriff's officials and NPS officials are working in conjunction with the FBI. FBI investigators are expected to remove the remains sometime later this afternoon and will work with the Marin County Coroner to determine the victim's identity and how they died, Dell'Osso said.