The body was transferred to a hospital at the eastern South Korean city of Sokcho near the border.
More than one million South Koreans have visited Mount Kumgang, just inside the North's border.
Relations have stalled since Lee Myung-bak, South Korea's new conservative president, took office six months ago with a tougher policy on the North.
However, just before the shooting on Friday, Myung-Bak proposed new negotiations between the Koreas and said he would respect earlier agreements from North-South summits, a softening of his earlier stance.
Meanwhile a second day of six-party talks on North Korea's nuclear programme is underway in Beijing.