FBI spokeswoman Vicki Anderson said the body was found in a shallow grave near Rolling Acres shopping mall in Akron, the Cleveland Leader reported.
Anderson said the cause of death and the victim's identification are under investigation but the FBI is working under the hypothesis the body could be that of a man who answered the ad.
The man, Timothy Kern, 47, of Massillon, Ohio, was last seen the morning of Sunday, Nov. 13, in the Plain Township area.
The Leader said he had posted a message on Facebook Nov. 10 about a "strange" job offer for a farm hand.
"Just got one of the strangest job offers. A good offer but strange," the posting said. "The job is to watch over 680 acres south of cambridge. Odd jobs and such but mainly just secure it. Trailer, utilities, salary. Drawbacks? No cell phone service, kids are up here, and i have to move this sunday."
Kern told family members he was to meet with the employer that Sunday morning and has not been heard from since. His family said it is unlike him to go without contact for so long.
An ad for a farm hand in southeastern Ohio has been used to lure people who are then robbed, police believe.
One man who responded to the ad was found dead, and another man escaped after being shot, the Leader said.
Two people are in custody, a juvenile and an adult.
Anyone with information about Kern's whereabouts is asked to call the FBI in Canton at 330-456-6200.