On Friday, a ventilation grate gave way, and more than two dozen people standing on it plunged some 20 meters (66 feet) -- or four stories -- into an underground parking structure below, a government accident response task force said.
In addition to the deaths, eleven people were injured, three seriously.
On Saturday, the body of the 37-year-old safety official was found on a street near his office, Yonhap news agency reported, citing police. They think he jumped to his death.
He left a brief message on his Facebook page. "I apologize to the victims. I'm sorry to my family."
On Friday, Prime Minister Chung Hong-won inspected the gaping concrete hole that swallowed up concertgoers.
Some media reports indicate the victims were standing on the grate in order to get a better view of the stage.
A witness told CNN affiliate YTN, "There was a sudden, loud screaming and when I turned, it looked as if people were being sucked down into a hole."
About 700 people were attending the concert, which featured South Korean artists, including the popular all-female group 4Minute, Yonhap reported.
A ferry sinking in April killed more than 300 people, many of them schoolchildren, and caused nationwide outrage.
Critics contend safety measures and regulation are not keeping pace with the fast-paced economic development in the country.