South Korean Prime Minister Chung Hong-won resigned on Sunday over the government's response to the ferry disaster.
The Sewol sank on a routine trip south from Incheon to Jeju, a holiday island, on 16 April.
"Keeping my post too great a burden on the administration," a sombre Chung said in a brief announcement.
Chung was booed and someone threw a water bottle at him when he visited grieving parents the day after the disaster.
President Park Geun-hye was also booed by some of the relatives when she visited a gym where families of the missing were staying.
More than 300 people, most of them students and teachers from one high school on a field trip, are dead, or are missing and presumed dead.
The children were told to stay put in their cabins, where they waited for further orders. The confirmed death toll on Sunday was 187.